Mutations Of Uncertain Significance Research Articles

Genetic and dermoscopic findings in a case series of children with oculocutaneous albinism.

Oculocutaneous albinism (OCA) is a genetic disease caused by disorders in melanin synthesis or distribution. In this descriptive study conducted in a tertiary care pediatric hospital, patients with a clinical diagnosis of OCA and genetic study were retrospectively recruited and underwent dermatological and ophthalmological exam, including optical coherence tomography (OCT) and digital dermoscopy. Our findings revealed milder OCA phenotypic expression in individuals harboring single pathogenic mutations in conjunction with polymorphisms, as well as in those with mutations of uncertain significance. Regardless OCA subgroup, severe phenotypes of OCA were associated with a higher number of mutations/polymorphisms in melanin biosynthesis genes and paler dermoscopic patterns, such as vascular pattern, which was the most common pattern in our series.

SAT281 Screening For Adrenocortical Insufficiency In Patients With X-linked Adrenoleukodystrophy

Abstract Disclosure: J. Berquist: None. R.N. Kiani: None. M.P. Wahl: None. Background: A 41-year-old male initially presented to neurology clinic for complaints of poor balance, lower extremity weakness, and numbness. He previously had exam findings of lower extremity spasticity and hyperreflexia, distal vibratory loss, positive Romberg, and difficulty with Tandem gait. His symptoms had been progressive following an ankle sprain 8 years earlier and he was treated with physical therapy and baclofen. He is highly active otherwise and enjoys rock climbing, which was difficult to do given his symptoms. Clinical Case: Genetic screening was performed to evaluate for hereditary spastic paraparesis, which resulted positive for a mutation in the ABCD1 gene with a p.Lys336Glu mutation of uncertain significance. Interestingly, this ABDC1 variant was not detected in submitted maternal sample, hence patient’s mutation likely occurred de novo. This variant is not established in population databases (gnomAD no frequency) but has been observed in at least one individual with clinical features of adrenomyeloneuropathy. X-linked adrenoleukodystrophy causes impairment of beta oxidation that leads to accumulation of saturated very long chain fatty acids (VFLA) in multiple tissues. There are many clinical phenotypes, but they are hallmarked by neurologic signs and symptoms. Although neurologic symptoms can often develop in childhood, they can be delayed and present in adulthood, as can adrenal insufficiency (AI). However, males are overwhelmingly likely to develop adrenocortical insufficiency compared to females. Our patient presented with a BMI of 22.94, HR 50 bpm, and blood pressure 120/76; reflecting his active lifestyle. Recent electrolytes were within normal limits, AM cortisol was 13.0, and ACTH 544.0 Given the elevated ACTH and known cause of adrenal insufficiency, we proceeded with ACTH stimulation test. Peak cortisol resulted at 13.1 (at 60 minutes) and he was started on replacement glucocorticoid therapy per body-surface area. Upon further literature review, patients can also develop loss of mineralocorticoid production. Renin and aldosterone were ordered and were both within normal limits. Conclusion: Males with adrenoleukodystrophy are at a much higher risk of developing adrenal insufficiency (AI) compared to females. Additionally, AI will often develop later in life, so a low threshold for screening should be present for the endocrinologist. Mineralocorticoid deficiency can also develop, although not as commonly. Loss of adrenal function can lead to patient demise, and therefore adrenal function needs to be closely evaluated in people with leukodystrophy. Presentation: Saturday, June 17, 2023

Characterization of Mutation of BRCA1 Gene at Chromosome 17q21 in Bangladeshi Women With Familial Breast Cancer

Breast cancer is the most common cancer among women in Bangladesh. About 69% cancer death of women is due to breast cancer. In Bangladesh the incidence rate of breast cancer is about 22.5 per 100000 female. Female who carries mutation in the BRCA1 gene have an 80% chance of developing breast cancer during their lifetime. Due to its high prevalence, genetic testing for BRCA1 mutation has become an integral part of clinical practice. This study was aimed to characterize the mutation at chromosome 17q21 by targeting BRCA1 gene among Bangladeshi women with familial breast cancer. This descriptive case series study was conducted in the Department of Biochemistry, Dhaka Medical College, Dhaka, from July 2017 to June 2018. In this study, thirty diagnosed breast cancer patients with family history breast cancer were selected according to the selection criteria from the Department of Surgery and Department of Radiotherapy, Dhaka Medical College, Dhaka. Mutations were detected by Next Generation Sequencing method. Characterization and clinical significance were verified from NCBI genome database. The study parameters were presence of mutation, types of mutation, clinical significance, frequency (%) of mutation. In this study, sixteen distinct mutations were found. Three pathogenic mutations (10%) were found among the patients which were nonsense mutations. Pathogenic mutations were c.5251C>T, c.2158G>T and c.1059G>A. Three mutations of uncertain significance with missense variant, five benign mutations of missense variant and five benign mutations of silent variant were also found among thirty patients. In this study we found that, Bangladeshi women with familial breast cancer had 10% pathogenic mutations. Early screening for BRCA1 gene mutations might provide better information for health to those who have family history of breast cancer.
 Bangladesh J Med Biochem 2018; 11(2): 17-23

E70 A new mutation of uncertain significance in Farber disease

Abstract Introduction Farber disease is a rare autosomal recessive lysosomal storage disorder. It is caused by a mutation in the ASAH1 gene, which results in a deficiency of acid ceramidase and subsequently an accumulation of ceramide in various tissues. The manifestations are diverse and the cardinal symptoms of the Farber disease triad include subcutaneous nodules, joint pain and hoarseness. Aims To recall the clinical features of this rare disease in order to avoid a late diagnosis and to inform about the identification of a novel mutation in a Moroccan patient known until now as a mutation of uncertain significance in the acid ceramidase gene. Method About a clinical case reported retrospectively with a prospective follow-up. Results We report the case of a fourteen-year-old boy born from healthy, consanguineous Moroccan parents after an uneventful pregnancy and delivery. He had normal development until the age of 9 months. The first symptoms appeared at the end of the first year of life with joint stiffness, hoarseness, subcutaneous nodules, blepharitis resulting in amblyopia, dental enamel defect, gingival hyperplasia, and severe failure to thrive, without any visceral manifestations. Routine laboratory investigations revealed normal hydroelectolytic, glycemic, hepatic, renal, and thyroid status. Standard radiography revealed diffuse bone demineralization, laryngoscopy showed laryngeal dyskinesia, echocardiography and abdominal ultrasound were normal. Biopsy of a nodule revealed hyalinosis deposition leading initially to the hypothesis of systemic hyalinosis. The diagnosis of Farber disease was suspected at the age of eight and definitively confirmed at the age of fourteen after a genetic study of ASAH1 revealing a novel compound homozygous mutation in exon 3 c.194T>G (p.Leu65Trp) whose significance was considered uncertain to date with an acid ceramidase enzyme assay that showed a markedly reduced leucocyte acid ceramidase activity, consistent with a homozygous status for acid ceramidase deficiency. Treatment with analgesics based on paracetamol and nonsteroidal anti-inflammatory drugs, with iron, calcium and vitamin D supplements was prescribed. Physiotherapy was recommended but was very difficult as the child is so painful. Discussion and Conclusion Farber disease is a rare condition with only about 200 cases identified worldwide. It is caused by mutations in the ASAH1 gene. The disease has a wide range of clinical presentations, and this case report highlights the challenge of diagnosis, with a long delay due to lack of awareness of the disease among clinicians. Furthermore, this case describes a novel homozygous mutation in the ASAH1 gene: c.194T>G (p.Leu65Trp) of the ASAH1 gene in a Moroccan patient, expanding the phenotypic spectrum of the disease. Genetic testing should be considered in patients with a clinical presentation consistent with the disease, supplemented by an acid ceramidase enzyme assay in case of doubt as was done in our patient. To date, there is no cure for Farber disease, and treatment is symptomatic and supportive. However, early diagnosis and appropriate management can help improve the quality of life for patients and their families. This case highlights the importance of further research in order to develop more effective treatments for this rare condition. Clinical trials are planned in the close future. Ethics The patient and his family members provided informed consent for publication of indirectly identifiable data.

C82 CARDIOMYOPATHIES AND GENETICS: ACTIVATION OF A SHARED PATH. INSIGHTS FROM CUNEO HOSPITAL

Abstract Introduction In the last few years, genetic investigation has become an active part of the diagnostic and therapeutic pathway of cardiological patients with cardiomyopathies. Genetic investigation assumes a key role in the clinical–decision–making process of the proband acquiring a potential role in changing clinical action. Patients referred for genetic screening are affected by hypertrophic, arrhythmogenic and dilated cardiomyopathy. In the dilated form it is now a well–established notion that some mutations are associated with increased arrhythmic risk, regardless of the ejection fraction. This link was implemented by the 2022 ESC guidelines on ventricular arrhythmias, these patients can in fact benefit from a more aggressive therapeutic approach for the purpose of preventing sudden death. Methods and results In 2022 a diagnostic process was activated in collaboration with the genetics laboratory. Twenty–two patients underwent genetic examination and genetic testing. Of these, 61% were patients with hypertrophic cardiomyopathy, 22% with dilated cardiomyopathy, 11% with arrhythmogenic cardiomyopathy and 6% with Fabry disease. Two HCM patients have mutations in the MYBPC3 gene. A patient with Fabry has an exonic mutation in the GLA gene associated with the late onset phenotype. Two patients have a negative NGS panel and one patient has a mutation of uncertain significance (VUS) in TTN. In the remaining genetic analysis is ongoing. Conclusions We believe, as clinical cardiologist who deal with the field of cardiomyopathies, in the importance to acquire an integrated vision where genetic diagnosis is added alongside the traditional tools of cardiological expertise, as a risk stratification tool and as an additional element of the decision–making process.

Clinical and genetic characterization of pediatric patients with Wilson's disease from Yunnan province where ethnic minorities gather.

Background: Wilson's disease (WD) is an autosomal recessive disease that is caused by mutations in the ATP7B (a copper-transporting P-type ATPase) gene. The disease has a low prevalence and is characterized by a copper metabolism disorder. However, various characteristics of the disease are determined by race and geographic region. We aimed to discover novel ATP7B mutations in pediatric patients with WD from Yunnan province, where there is a high proportion of ethnic minorities. We also performed a comprehensive analysis of ATP7B mutations in the different ethnic groups found in Southwest China. Methods: We recruited 45 patients who had been clinically diagnosed with WD, from 44 unrelated families. Routine clinical examinations and laboratory evaluations were performed and details of age, gender, ethnic group and symptoms at onset were collected. Direct sequencing of the ATP7B gene was performed in 39 of the 45 patients and their families. Results: In this study, participants came from seven different ethnic groups in China: Han, Bai, Dai, Zhuang, Yi, Hui and Jingpo. Three out of ten patients from ethnic minorities presented with elevated transaminases, when compared to the majority of the Han patients. Forty distinct mutations (28 missense, six splicing, three non-sense, two frameshift and one mutation of uncertain significance) were identified in the 39 patients with WD. Four of the mutations were novel and the most frequent mutation was c.2333G > T (p.R778L, allelic frequency: 15.38%). Using the phenotype-genotype correlation analysis, patients from ethnic minorities were shown to be more likely to have homozygous mutations (p = 0.035) than Han patients. The patients who carried the c.2310C > G mutation had lower serum ceruloplasmin levels (p = 0.012). In patients with heterozygous mutations, c.3809A > G was significantly associated with ethnic minorities (p = 0.042). The frequency of a protein-truncating variant (PTV) in Han patients was 34.38% (11/32), while we did not find PTV in patients from ethnic minorities. Conclusion: This study revealed genetic defects in 39 pediatric patients with WD from Yunnan province. Four novel mutations were identified and have enriched the WD database. We characterized the genotypes and phenotypes in different minorities, which will enhance the current knowledge on the population genetics of WD in China.

Clinical and Pathologic Characteristics of Essential Thrombocythemia (ET) Patients Harboring Calreticulin (CALR) Mutations

Introduction: Calreticulin (CALR) mutations comprise of a significant proportion of essential thrombocythemia (ET) patients. The frequency, types and clinical characteristics of ET patients with CALR mutations have not been widely studied. Moreover, ET patients with calreticulin (CALR) mutations are reported to have different characteristics and complications as compared to ET patients with other mutations. Methods: We studied clinical characteristics and type of CALR mutations in ET patients diagnosed and managed at our center. Data were collected retrospectively from electronic health records and patients' files. We collected information on age, gender, presentation symptoms, history and development of vascular complications during follow up, risk category, blood counts at diagnosis, type of CALR mutation, therapy received, and any association of mutations with clinical and laboratory parameters. Results: Twenty patients were diagnosed with ET harboring CALR mutations with a median age of 51 years (range 25-66); 14 (70%) were males. The diagnosis was made in most patients because of an incidental finding of high platelet count and only 3 (15%) had symptoms at diagnosis. One patient presented with limb ischemia at diagnosis while 3 patients had prior history of arterial vascular events. Majority of the patients were in the low-risk category (65%), while 5 (25%) patients had high-risk disease at diagnosis. Seventeen (85%) patients were treated with aspirin, 15 (75%) with hydroxyurea, and 3 with anagrelide. Median platelet count at diagnosis of ET was 960 x 109 (range 463-1584; reference 150-400). Eight (40%) patients had platelet counts above 960 x 109 at presentation. Table 1 shows the genetic variants, frequency and the type of CALR mutations. Two patients had mutations of uncertain significance in the CALR gene. After a median follow up of 48 months (range 2-204), only one patient developed thrombosis (pulmonary embolism); this patient also had arterial thrombosis previously. One patient with type 2 mutation progressed to myelofibrosis (MF) and remains alive on ruxolitinib and regular blood transfusions after 84 months of follow up post MF diagnosis. One 56-year-old male patient underwent surgery for coronary artery disease and severe aortic stenosis and died of hemothorax and multiple complication. Vascular events in 3 of the 4 patients occurred in those with type-2 mutations. Conclusions: Majority of ET patients harboring CALR mutations were males and presented without symptoms with incidental diagnosis, and had low risk disease. Type 1 and 2 mutations occurred with almost equal frequency. Vascular complications were infrequent after diagnosis and only one patient developed thrombosis during follow up. These finding are consistent with other studies of ET with CALR mutations. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Analytical and clinical validation of a custom 15-gene next-generation sequencing panel for the evaluation of circulating tumor DNA mutations in patients with advanced non-small-cell lung cancer.

BackgroundThis is a pilot proof-of-concept study to evaluate the utility of a custom 15-gene circulating tumor DNA (ctDNA) panel as a potential companion molecular next-generation sequencing (NGS) assay for identifying somatic single nucleotide variants and indels in non-small-cell lung cancer (NSCLC) patients. The custom panel covers the hotspot mutations in EGFR, KRAS, NRAS, BRAF, PIK3CA, ERBB2, MET, KIT, PDGFRA, ALK, ROS1, RET, NTRK1, NTRK2 and NTRK3 genes which serve as biomarkers for guiding treatment decisions in NSCLC patients.MethodThe custom 15-gene ctDNA NGS panel was designed using ArcherDX Assay Designer. A total of 20 ng or 50 ng input ctDNA was used to construct the libraries. The analytical performance was evaluated using reference standards at different allellic frequencies (0.1%, 1%, 5% and parental). The clinical performance was evaluated using plasma samples collected from 10 treatment naïve advanced stage III or IV NSCLC patients who were tested for tissue EGFR mutations. The bioinformatics analysis was performed using the proprietary Archer Analysis Software.ResultsFor the analytical validation, we achieved 100% sensitivity and specificity for the detection of known mutations in the reference standards. The limit of detection was 1% allelic frequency. Clinical validation showed that the clinical sensitivity and specificity of the assay for detecting EGFR mutation were 83.3% and 100% respectively. In addition, the NGS panel also detected other mutations of uncertain significance in 6 out of 10 patients.ConclusionThis preliminary analysis showed that the custom 15-gene ctDNA NGS panel demonstrated good analytical and clinical performances for the EGFR mutation. Further studies incorporating the validation of other candidate gene mutations are warranted.

The correlation between tumor mutation burden and TP53 or CHEK2 germline mutations in malignant tumors.

e22527 Background: Li-Fraumeni syndrome (LFS) is a rare autosomal dominant cancer predisposition syndrome, mainly caused by the lack of tumor suppressor gene TP53. The LFS related tumors include breast cancer, brain tumors, malignant sarcoma, bone cancer and central nervous system tumors. In addition to TP53 germline mutations, studies have shown that CHEK2 is also a susceptibility gene for LFS, and CHEK2 germline mutations is related to a series of cancer types. However, the correlation between tumor mutation burden (TMB), age, gender, PD-L1 expression and TP53 or CHEK2 germline mutations in malignant tumors remains unknown. Methods: In this study, we retrospectively analyzed the mutation characteristics of TP53 or CHEK2 germline mutations in patients with solid tumors without selecting age or family history. We identified 631 patients harboring TP53 or CHEK2 mutations from 9337 patients with malignant solid tumors. According to the ACMG (American College of Medical Genetics and Genomics) guidelines in pathogenicity, the 631 patients in the retrospective cohort were divided into three groups, including P/LP group (with pathogenic or likely-pathogenic mutations), VUS group (with uncertain significance mutations) and B/LB group (with benign or likely-benign mutations). We also analyzed the differences in TMB, age, gender and PD-L1 expression among the three groups. Statistical significance was defined as P-value less than 0.05. Results: The 631 (631/9337) patients carried TP53 or CHEK2 germline mutations were identified, in which 33 patients with pathogenic mutations and 15 patients with likely-pathogenic mutations. These pathogenic or likely-pathogenic mutations mainly occurred in lung cancer, brain tumors, colorectal cancer and liver cancer, accounting for about 35.4%, 20.8%, 16.7% and 12.5%, respectively. Among the three groups, TMB was significantly different between P/LP group and B/LB group (P = 0.037), and the B/LB group was higher. In addition, we found that the three groups had no significant differences in age, gender and PD-L1 expression. Conclusions: Our data showed that 0.823% (48/8535) malignant solid tumor patients carried TP53 (28/48) or CHEK2 (20/48) germline pathogenic or likely_ pathogenic mutations. In addition, the TMB value in B/LB group was significantly higher than that in P/LP group. The other characteristics of LFS will be studied in the future.

Application of next-generation sequencing in detection of BRCA1/2 and homologous recombination repair pathway multi-genes germline mutation and correlation analysis

Objective: To investigate the germline mutation status of related genes in breast cancer patients and high-risk individuals by next-generation sequencing. To analyze the correlations between homologous recombination repair (HR) pathway gene mutation status and clinicopathological characteristics of breast cancer patients. To supplement the database of breast cancer related gene mutations in Chinese population. Methods: This study is a cross-sectional study. From October 2020 to September 2021, whole blood samples were collected from 350 breast cancer patients and 49 high-risk individuals, admitted to Peking University People's Hospital and accepted genetic testing voluntarily. Germline mutations in 32 breast cancer related genes were detected by NGS. The clinicopathological characteristics, including age at the onset, family history, unilateral/bilateral tumor, Luminal typing (Luminal A subtype, Luminal B subtype, HER2-enriched subtype and triple negative breast cancer), tumor size and metastasis, were analyzed, and the correlations between HR pathway gene mutation status and clinicopathological characteristics were analyzed by Chi-squared test and Fisher's exact probability test. Results: Among 350 breast cancer patients, 64 (18.3%) cases carried gene pathogenic mutations (including pathogenic and likely pathogenic mutations), including 47 (13.4%) in BRCA1/2, 16 (4.6%) in non-BRCA1/2 genes, 1 (0.3%) in BRCA2 and FANCL. Among 49 high-risk individuals, 7 (14.3%) cases carried gene pathogenic mutations, including 6 (12.3%) in BRCA1/2 and 1 (2%) in ATM genes. BRCA1/2 pathogenic mutations were associated with age at the onset (18%, 8.7%, χ²=6.346, P=0.012), and the BRCA1/2 pathogenic mutation frequency was higher in patients diagnosed at age ≤45 years. HR pathway gene mutations (including pathogenic, likely pathogenic and uncertain significance mutations) were correlated with unilateral/bilateral tumor (49.5%, 68.4%, χ²=4.841, P=0.028) and Luminal typing (45.7%, 62.2%, 32%, 60%, χ²=12.004, P=0.007), and the HR mutation frequencies were higher in patients with bilateral tumor, Luminal B breast cancer and triple negative breast cancer (TNBC). Conclusion: The BRCA1/2 pathogenic mutation frequency in high-risk individuals is similar to that in breast cancer patients, and BRCA1/2 testing is helpful to guide breast cancer screening and prevention in high-risk individuals. Patients with early onset breast cancer, bilateral breast cancer, Luminal B breast cancer and TNBC have higher mutation frequencies of HR pathway genes, and HR pathway genes testing should be conducted as soon as possible to provide laboratory evidence for diagnosis, treatment, prognosis and risk evaluation of breast cancer.

Abstract 43: Prevalence of islet-autoantibodies and monogenic diabetes in children with recent onset type 1 diabetes mellitus: A multicenter study

Background: Previous smaller studies have shown higher prevalence of islet-antibody negative Type 1 diabetes mellitus (T1DM) among Indians compared to Caucasians. Islet-antibody negative (Type 1B) diabetes is not well characterized.Aims and Objectives: To study the prevalence of islet-autoantibodies, characterize type 1B diabetes, and determine the role of enterovirus infections and monogenic diabetes in children and adolescents with recent onset T1DM.Results: Among 111 patients, frequency of islet-autoantibody positivity were: GAD65-73%, IA2-35% and ZnT8-34%. 20 (18%) were negative for all 3 islet-autoantibodies. There were no significant clinical, biochemical or HLA allelic frequency differences between antibody negative and positive group. None of the ninety subjects tested showed evidence of enterovirus infection in serum by RT-PCR. Of the seven Type 1B patients without ketoacidosis tested, 2 had pathogenic mutations: one each in WFS 1 [homozygous c.2006A>G (p.Tyr669Cys)] and HNF4a [heterozygous c.998G>A (p.Arg333His)] loci. An additional 2 subjects had mutations of uncertain significance: one each in WFS 1 [heterozygous c.1522_1523del (p.Tyr508CysfsTer34)] and ABCC 8 [Heterozygous c.3784G>A (p.Ala1262Thr)] loci.Conclusions: A significant proportion of patients with T1DM were negative for islet antibodies at onset, but did not differ clinically or biochemically. Monogenic diabetes was found in a proportion of patients with type 1B diabetes.

HP39: PMP22 neuropathies: Charcot-Marie-Tooth disease type 1A in a boy and changes in electroneuromyography

Charcot-Marie-Tooth (CMT) disease is the most frequent inherited neuropathy, affecting 1/1500 to 1/10000 (60%-70% of all CMT and is caused by a duplication on chromosome 17p11.2 leading to an overexpression of the Peripheral Myelin Protein 22 (PMP22)). CMT1A characterized by distal muscle weakness and atrophy, sensory loss, and slow nerve conduction velocity. Early diagnosis is necessary for further prognosis and management of the patient. At the boy from 9 years parents noticed gait disturbances: it was difficult to step on a heel. Within a few years, the symptoms progressed and there was a sensitivity disorder. According to the neurological status, the knee reflexes were reduced and there were no Achilles. We performed electroneuromyography and recorded a significant decrease in motor and sensory responses (less than 1 μV). Needle myography showed secondary denervation changes in the muscles. We sent the patient's blood for genetic analysis (Comprehensive Neuropathies Panel). We received a Pathogenic variant, Gain (Entire coding sequence), was identified in PMP22. This variant is a gross duplication of the genomic region encompassing exons 2-5 of the PMP22 gene. Therefore, it is assumed that the entire gene is duplicated. Duplications of the region on chromosome 17p11.2 which contain the PMP22 gene cause Charcot-Marie-Tooth type 1A (CMT1A). The patient was also found to have mutations of uncertain significance: in SCN11A (associated with autosomal dominant hereditary sensory and autonomic neuropathy type 7) and SCN9A. After the diagnosis, we also provided him with recommendations for multidisciplinary management together with rehabilitation specialists and orthopedists.

Family screening in brugada syndrome patients

Abstract Background Brugada syndrome (BS) is a rare inherited channelopathy associated with sudden cardiac death (SCD) and family screening (FS) of index patients (pts) is recommended. However, data about pts identified through FS is lacking. Aim To compare index pts to non-index pts identified through systematic FS. Methods Single-center retrospective study of BS pts followed by the Arrhythmology Department. FS was offered to 1st degree relatives of all index pts through primary care services and a once-weekly voluntary open appointment. Genetic counselling was performed when indicated. Index and non-index pts were compared regarding baseline characteristics and events during the follow-up (syncope of probable arrhythmic origin, ventricular tachycardia/ventricular fibrillation (VT/VF) and SCD). Results We included 165 pts (61% males, mean age 47±15 years) and 72 (44%) were identified through FS. Non-index pts were diagnosed at a younger age (42±14 vs 51±14 years, p <.001), were more often female (57% vs 25%, p<.001), were diagnosed predominantly through provocative test with ajmaline/flecainide (88% vs 47%, p<.001) and had less documented spontaneous type 1 ECG pattern (17% vs 59%, p<.001). A type 2 pattern was identified in 18 (25%) non-index pts. Genetic testing was performed in 38 (53%) non-index pts: 6 had a pathogenic SCN5A mutation, 18 a likely pathogenic SCN5A mutation and 12 a mutation of uncertain significance. At diagnosis, 24 (33%) non-index pts had history of syncope, 3 (4%) had nocturnal agonal respiration and 11 (15%) had palpitations with no differences between both groups (p=.119). Non-index pts were less likely to implant a cardioverterdefibrillator (14% vs 38%, p=.001). During a median follow-up of 28 (IQR 16–41) months, 10 (6%) pts had an event - 2 (3%) in the non-index group (2 syncope) and 8 (9%) in the index group (1 syncope; 7 VT/VF) - with no significative differences between groups (p=.432). There were nocardiovascular deaths. Conclusions FS identified a considerable proportion of BS pts. Non-index pts were younger at the time of the diagnosis and had less spontaneous type 1 pattern. No differences were found in events between index and non-index pts, however, the event rate was low. Systematic FS can identify individuals at risk of SCD earlier, allowing close monitoring and, when indicated, appropriate treatment. Funding Acknowledgement Type of funding sources: None.

MO045THE APPLICATION OF A NGS KIDNEY PANEL REVEALED KEY CHALLENGES OF PKD1-2 ANALYSIS: INTERPRETATION OF MISSENSE VARIANTS, SIGNIFICANCE OF VARIANTS IN DUPLICATED REGIONS AND HIGH ALLELIC HETEROGENEITY

Abstract Background and Aims Genetic testing has changed the clinical management of inherited kidney diseases patients, improving prognosis, surveillance and therapy. On the other hand, it has put geneticists and clinicians in front of new challenges, as the heterogeneity of these disorders and the high number of variants, with no clear genotype-phenotype correlation. Method 108 patients underwent genetic analysis through a kidney focused NGS panel, named Nephroplex, containing 119 genetic loci associated with inherited kidney disorders. The study aimed to addressed the genetic landscape of cystic individuals and to analyze PKD1 and PKD2 variants in non-cystic individuals. Results Following diagnostic criteria, patients were divided as cystic kidney diseases (n=36) and non-cystic kidney diseases (n=72). Among the group of cystic patients, a causative mutation was detected in 51% of cases. We found thirty-seven PKD1 and PKD2 variants in 26 out of 35 individuals. In particular, 12 variants were shown to be damaging and nine of that were reported in public database, as CLINVAR and Mayo Clinic databases. Among pathogenic variants, twelve were truncating and the remaining were missense variants. Of note, 7 out of 12 damaging PKD1 mutations were located in duplicated regions. Moreover, in three cystic patients, we found a (i) a frameshift hemizygote OFD1 mutation (ii) compound heterozygote PKHD1 variants and (iii) a frameshift MUC1 variant, framing the diagnosis of oro-facio-digital type 1, autosomal recessive polycystic kidney disease and autosomal dominant tubulointerstitial disease, respectively. Interestingly, we detected 28 PKD1-2 rare variants in 21 out of 75 adult non cystic patients (28%). The most were observed in PKD1 genes (82% vs 18% in PKD2). Eighteen of 28 variants were described in the literature as likely benign or as mutations of uncertain significance, while we found 10 novel variants. In silico analysis revealed as pathogenic a frameshift mutation located in exon 15. Of note, the great part of these variations reside into the duplicated PKD1 regions. Conclusion Our data showed that genetic analysis of ADPKD retains unique challenges, given the high degree of homology of PKD1 with his pseudogenes and the high allelic heterogeneity in non-cystic individuals.

Therapeutic effect of DDR pathway with different functional annotations for immune checkpoint inhibitor.

2611 Background: DNA damage response and repair (DDR) pathway-related gene mutations have been reported to predict the efficacy of immune checkpoint inhibitor (ICI). However, therapeutic effect of DDR pathway with different functional annotations is not fully studied. Here we explore the relationship of DDR pathway with different functional annotations and clinical outcomes in public cohorts of immunotherapy and chemotherapy. Methods: Genetic testing and clinical outcomes data were obtained from the public clinical cohorts across 10 tumor types. 232 DDR pathway-related gene were assigned to eight pathway according to the literature. Nine predictive models for the mutation pathogenicity were included in the analysis, of which at least five returned positive results were defined as deleterious mutations. All annotations were according to the American College of Medical Genetics (ACMG) standards and guidelines. To explore the association between DDR pathways and ICI, DDR pathway mutation is grouped. Patients, who harbored mutations in two or more DDR pathways and meanwhile had deleterious mutation in at least one DDR pathway, were enrolled in group A. Patients, who harbored deleterious mutations in only one DDR pathway or had only uncertain significance mutations, were enrolled in group B. Patients with no DDR gene mutations were enrolled in Group C. We analyzed relation of the group and survival outcomes in four public cohorts. Results: Of 4 clinical cohort analyzed, the group A treated with ICI has the best PFS or OS outcomes. However, the comparison of group B and group C is not coincide across different cohorts. Treatment is the key factor that influents the relation of DDR pathway mutations and clinical outcomes. As shown in POPLAR/OAK cohort, patients in group C has the best PFS (p=0.0381) or OS (p=0.0350) outcome when treated with chemotherapy, but patients in group A has the best PFS (p=0.0083) or OS (p=0.0222) outcome when treated with ICI. Conclusions: When treated with ICI, patients with at least one deleterious mutation and another deleterious or uncertain significance mutation has the best PFS or OS outcomes, but not for chemotherapy. Our study suggested that DDR pathway with deleterious mutations might be a potential predictive factor for immunotherapy.[Table: see text]

The Panorama of Primary Angioedema in the Brazilian Population

Primary angioedema (PA) is a complex disorder, presenting multiple hereditary (hereditary angioedema) and acquired subtypes (acquired angioedema). Despite a very similar clinical presentation among subtypes, the differential diagnosis is limited by the difficulty to identify bradykinin-mediated PA and the lack of specific biomarkers. To report the clinical and genetic features of Brazilian patients with PA. Brazilian patients referred from 50 centers were diagnosed on the basis of clinical symptoms, C1 inhibitor (C1-INH) and C4 plasma measurements, and DNA sequencing of genes associated with hereditary angioedema. We characterized 92 patients with acquired angioedema and 425 with HAE: 125 with C1-INH deficiency, 180 with F12 mutations, and 120 of unknown cause. Thirty-one different mutations were identified in SERPING1 and 2 in F12, in addition to 2 mutations of uncertain significance in the ANGPT1 gene. The molecular diagnosis was decisive for 34 patients with HAE without family history, and for 39% of patients with inconsistent biochemical measurements. The median delay in diagnosis was 10 years, with a maximum of 18 years for HAE with C1-INH deficiency. Androgens and tranexamic acid were the most used drugs for long-term prophylaxis in all the PA subtypes, and they were used on demand by 15% of patients. Only 10% of patients reported the use of specific medication for HAE during attacks. Our analysis exposes a broad picture of PA diagnosis and management in a developing country. Complement measurements presented considerable inconsistencies, increasing the diagnosis delay, while patients with PA with normal C1-INH remain with an inaccurate diagnosis and unspecific treatment.

Mutations of uncertain significance in heterozygous variants as a possible cause of severe short stature: a case report

BackgroundLinear bone growth is achieved by the division of chondrocytes at the growth plate and is regulated by endocrine and paracrine factors such as growth hormone. Mutations that negatively affect chondrogenesis can be a contributor to short stature. One such mutation can occur in the ACAN gene, causing short stature and advanced bone age. Similarly, mutations in growth hormone receptors (GHR) can lead to Laron syndrome (LS), one of the several disorders that are collectively called growth hormone insensitivity syndrome (GHI). Another example is Floating-Harbor syndrome (FHS), a rare autosomal dominant due to mutations in the SRCAP gene that can also result in short stature.Case presentationWe report the case of a 6-year-old female with concomitant mutations in the three genes mentioned above. The mutations reported here were found on genetic studies and are usually benign, causing a variant of undetermined significance. However, our patient’s phenotype could only be explained by the compounded effects of pathogenic mutations of these genes. Some of the same mutations were also found in the patient’s father and her paternal grandfather. Both also presented with short stature, though not to the same degree as our patient. While these mutations are often reported to be insignificant, they gave rise to severe short stature and a specific phenotype in the patient when presented together. We think that even though the GHI spectrum is inherited through an autosomal recessive pattern, the sum of these heterozygous mutations resulted in severe short stature despite the limited GHI seen in our patient, the father, and the grandfather, through a rare ACAN and SRCAP mutation that, to our knowledge, has not been previously reported as a pathogenic mutation in the literature.ConclusionWe investigated the possible synergistic effects of these variations on exacerbation or masking of the signs and symptoms of GHI with the hope of providing a better understanding of these genes and their function through our rare case.

Abstract P6-08-31: BRCA1 interacting protein C-terminal helicase 1 (BRIP1) as a cancer susceptibility gene

Abstract Background: Breast cancer is the most common cancer as well as the most common cause of cancer associated deaths in women worldwide. National Comprehensive Cancer Network has detailed criteria for identifying patients at risk for hereditary breast and ovarian cancer syndromes. Many multigene genetic testing panels are in use for screening and prognostication purposes. While pathogenic mutation in BRCA 1 and 2 mutations have been established as risk factors for developing breast cancer, the association of other germ line mutations with breast cancer is less defined. BRCA1 interacting protein C-terminal helicase 1 (BRIP1) influences the DNA repair ability as well as tumor suppressor function of BRCA1 and is associated with increased risk of ovarian cancer. Studies looking at association of BRIP1 mutation with risk of breast cancer have provided conflicting data and currently, BRIP1 is not implicated in causing breast cancer. Methods: We conducted chart review of patients who were referred for genetic testing at the Lipson Cancer Institute/Rochester General Hospital, Rochester, NY and tested positive for BRIP1 mutation alone. Samples were sent to Myriad Genetics for Integrated BRACAnalysis® testing with myRisk® panel looking at 35 genes for mutation. BRIP1 mutations with abnormal protein production and/or function thought to increase risk for ovarian cancer (pathogenic or likely pathogenic) are reported as clinically significant. BRIP1 mutations with currently insufficient data to determine an increased risk are reported as variations of uncertain significance. The panel does not report benign and likely benign mutations. Results: We found nine patients who tested positive for BRIP1 mutation and were negative for other genomic alteration including BRCA1 and BRCA2 mutation (Table 1 and 2). Four patients carried the known high risk BRIP1 mutation and five carried BRIP1 mutations of undetermined significance. One of four patients with known high risk BRIP1 mutations had a personal history but no family history of breast cancer while the remaining three had a family history but no personal history of breast cancer. All five patients with BRIP1 mutations of uncertain significance had both personal and family history of breast cancer. Conclusion: The known high risk BRIP1 mutations are probably not associated with increased risk of breast cancer. However, at least some of the BRIP1 mutations of uncertain significance are likely very significant and associated with increased risk of breast cancer. This association needs to be confirmed in a larger patient population. Table 1: Carriers of BRIP1 variations of uncertain significanceSerial NumberAge at time of screeningPositive BRIP 1 mutation Personal history of breast cancerFamily history of breast cancerAncestry164BRIP1 mutation, c.817A>GYesYesGerman/ Irish278BRIP1 mutation, c. 2220G>TYesYesHolland344BRIP1 mutation, c3237T>GYesYesAfrican430BRIP1 mutation, c.380-17T>AYesYesIrish/ English/ German555BRIP1 mutation, c.139C>GYesYesScottish Table 2: Carriers of high risk BRIP1 mutationsSerial NumberAge at time of screeningPositive BRIP 1 mutation Personal history of breast cancerFamily history of breast cancerAncestry169BRIP1 mutation, c.2255_2256delYesNoItalian/ Hungarian263BRIP1 mutation, c548delNoYesFrench Canadian337BRIP1 mutation, c.1045G>CNoYesDutch460BRIP1 mutation, c.2099T>ANoYesUnknown Citation Format: Mukul Singal, Manasi M Godbole, Kim Povenzano, Beth Elmore, Mehul P Patel. BRCA1 interacting protein C-terminal helicase 1 (BRIP1) as a cancer susceptibility gene [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P6-08-31.

Identifying Fabry patients in dialysis population: prevalence of GLA mutations by renal clinic screening, 1995-2019.

Fabry disease (FD) is a rare X-linked genetic disorder of glycosphingolipid catabolism caused by mutations in the GLA gene. Its heterogeneous presentation, the paucity of specific early markers, and the absence of a genotype-phenotype correlation are associated with a delayed or missed diagnosis. The true prevalence of FD remains so far unknown. A systematic search of FD screening studies in dialysis patients published from January 1995 until January 2019 was performed to reanalyze the prevalence of GLA mutations in this population after assigning their correct phenotype. Twenty five screening studies involving 39,621 dialysis patients were included. Of them, 116 [91 males (0.23%) and 25 females (0.06%)] were positive to the GLA sequencing analysis. 56 (48.2%) had benign variant, 52 (44.8%) a pathogenic GLA mutation (39 classic and 13 late onset mutations) and 8 (6.9%) a mutation of uncertain significance. The overall prevalence of GLA variants was 0.24% [CI 95%, 0.17-0.32] while the overall prevalence recalculated on basis of only pathogenetic mutations was 0.14% [CI 95%, 0.08-0.20]. This difference was significant (P = 0.048). Although the real prevalence of classic FD is low, the screening in the high-risk renal population remains of primary interest as an early diagnosis is fundamental for a timely specific therapy; moreover, the identification of index cases could allow patients' relatives to be investigated and promptly treated.

Abstract P4-03-09: Genetic and hereditary factors in breast cancer: Experience in a mastology service on analysis of genetic tests in high risk women

Abstract Background: Breast cancer is the most prevalent cancer in women in Brazil. The estimate by 2018 is 59,700 new cases. Of these, 10 to 15% are hereditary, caused by mutations in susceptibility genes that increase the risk of disease onset. These types of mutations can occur in several genes, each associated with different risks of developing the pathology. In hereditary breast-ovarian syndrome, the most frequently altered genes are BRCA1 and BRCA2. Mutations of these genes are associated with a 70-85% risk of developing breast cancer during life, but we know that there are other types of genetic alterations at risk of developing breast, ovarian, or other cancers - many are of uncertain significance and others, less known, appear to have high pathogenic potential. Thus, individuals identified with hereditary risk for developing breast or ovarian cancer should have intensive follow-up and genetic counseling. Materials and methods: A retrospective study was carried out between 2015 and 2018. The charts of each of the patients submitted to genetic counseling with a total of fifteen women were analyzed. Eleven of these, performed genetic tests to evaluate mutations in BRCA1 and 2, and four patients extended panels. Subsequently, a statistical analysis of the data was performed and the results were analyzed thanks to the informed consent that the patients signed. Results: Among the fifteen cases the age ranged from 27-68 years. Fifteen patients were analyzed, twelve with diagnosis of breast cancer and three without. In the eleven women who tested for BRCA1/2, 27% had mutations for these types of genes and three pathogenic variants of the genes. In the four who did the extended test, three had mutations in six types of genes, two with mutations of uncertain significance(VUS) and one pathogenic variant of the BLM gene. The indications for the exams were: 1)breast cancer patients: five cases with triple negative carcinomas and age less than 60 years-41.66%; 2)four with family history-33.33%; 3)three only by age-25%. In those without breast cancer the indications were family history. The majority of cases were requested for triple negative neoplasia, in which two cases presented mutation(40%) and three cases without mutation(60%), the two mutations in the BRCA1 and BRCA2 genes, one in each of them and none in VUS . In the four cases with a family history, two had mutations and two did not(50%) - two in BRCA 2 and one in VUS. In the three cases without cancer was found mutation in only one of them and with important family history was found mutation in one case(BRCA2). Conclusions: Mutations in BRCA1/2 genes are associated with susceptibility to develop breast-ovarian cancer. Currently these mutations are responsible for only a minority of familial cases and we also find variants of uncertain and pathogenic behavior. Intensive research to identify other types of genetic mutations that could be responsible for a significant percentage of breast cancer in BRCA1/2 negative families, as well as assessing their importance, appear to be necessary. As already published by other authors, although our casuistry is small, we also call attention to the presence of mutations in young patients with triple negative breast carcinomas. Citation Format: Chagas SR, Pineres MdRS, Chagas CR, Vieira RJ. Genetic and hereditary factors in breast cancer: Experience in a mastology service on analysis of genetic tests in high risk women [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P4-03-09.