Obligate Carriers Research Articles

Haemophilia testing of young girls in Canada: Describing the current recommendations for factor level and genetic testing and the experiences of Canadian parents.

It is widely acknowledged that haemophilia affects women and girls, yet current testing recommendations for factor level and genetic testing vary and do not universally incorporate updated research. Canadian parents have expressed frustration at inconsistent recommendations and reported instances where delayed testing led to missed diagnosis and preventable bleeding. Study aim was to explore and describe the practice of haemophilia-related testing of young girls in Canada. A mixed methods study was carried out with two populations: (1) Nurses working in haemophilia care completed a survey regarding the current testing recommendations of their Haemophilia Treatment Centre (HTC), (2) Parents of obligate or potential haemophilia carriers completed a structured interview with questions about their family experience of haemophilia and testing decisions for daughters. Twenty-six survey responses were received and showed wide variation in the usual recommendations of Canadian HTCs. Different factor level testing recommendations may be given to obligate and potential carriers despite no difference in bleeding risk. Only a minority of HTCs currently recommend an early baseline factor level (<10 years) to obligate carriers (27%) or potential carriers (15%). For genetic testing of potential carriers, 70% of HTC would approve a family request for genetic testing of a minor with specific conditions. The majority of parents interviewed felt dissatisfied with their testing experience (58%) and highlighted many issues related to delayed testing recommendations. Updated, nationally affirmed testing recommendations are needed that align with research on bleeding in women and girls affected by haemophilia.

Molecular Pathology of Myotonic Dystrophy Type 1 in Iceland.

Myotonic Dystrophy type 1 (DM1) is an autosomal dominant disease with anticipation due to increased number of CTG repeats in the DMPK gene. This retrospective, cohort study in Iceland assessed prevalence of DM1, molecular pathology, and patient ascertainment. Data was collected from all major hospitals in Iceland, Medical Director of Health, and independent clinics. Cohort criteria were diagnosis of DM1 on January 1, 2021, or time of death. Population-based Icelandic Genealogy Database of the Genetical Committee at the University of Iceland was used for genealogy. In Iceland, 221 individuals, including 19 obligate carriers, had been diagnosed with DM1 of which 144 were alive giving a point prevalence of 39 per 100,000 (four times the world average of 9.3). Genealogy analysis identified 45 first-degree families. Age-adjusted prevalence ranged between 11 and 66 per 100,000. Average potential years of life lost were 20.5 per person. Where information was available, 63% of ascertainment was based on family history in cascade testing. The differences in age-adjusted prevalence suggest that the overall point prevalence is an underestimation due to underdiagnosis in younger age groups and lethality in oldest age group. Our data supports use of cascade testing to improve DM1 ascertainment.

A Splice Site Variant in ADAMTS3 Is the Likely Causal Variant for Pulmonary Hypoplasia with Anasarca in Persian/Persian-Cross Sheep.

Pulmonary hypoplasia with anasarca, or hydrops fetalis, is characterized by stillbirth, diffuse oedema, and generalized lymph node hypoplasia. The enlarged fetus frequently causes dystocia. The disease has been reported in cattle and sheep as an inherited condition with a recessive mode of inheritance. This is the first report of the disease in Persian/Persian-cross sheep in Australia. Affected fetuses were reported from three flocks, and a total of eleven affected, eleven obligate carrier, and 188 related Persian/Persian-cross animals were available for analysis, as well as unrelated control animals. SNP genotyping revealed a region of homozygosity in affected animals on ovine chromosome six, which contained the functional candidate gene ADAMTS3. Whole genome sequencing of two affected fetuses and one obligate carrier ewe revealed a single nucleotide deletion, ENSOARG00000013204:g.87124344delC, located 3 bp downstream from a donor splice site region in the ADAMTS3 gene. Sanger sequencing of cDNA containing this variant further revealed that it is likely to introduce an early splice site in exon 14, resulting in a loss of 6 amino acids at the junction of exon 14 and intron 14/15. A genotyping assay was developed, and the ENSOARG00000013204:g.87124344delC segregated with disease in 209 animals, allowing for effective identification of carrier animals.

PSIV-9 Pedigree tracing to determine the origin of the golden coat phenotype within the Golden American Saddlebred horse

Abstract With the incorporation of the Golden American Saddlebred Horse Association (GASHA) into the American Saddlebred Horse Association (ASHA), breeding specifically for coat color within the breed registry became less of an emphasis for horse breeders. Nevertheless, historical documentation of the horses making up the foundation of the GASHA through the application of pedigree tracing holds value in understanding the origin of the breed and its coat color. This can be of value to horse breeders targeting a specific coat color as the study of coat colors is a relatively new field of research within equine science. Thus, the objective of this study was to document the historical origins of the GASHA through pedigree tracing to determine the influence of the dilution genes that produce the golden coat phenotype. A random sample of 550 horses was obtained from the Official Directory of GASHA. Using the All-Breed Data Base, sampled horses were entered and examined for pedigrees suitable for analysis of color inheritance, and of these, 507 were found to have extended pedigrees with documented coat colors that were used for this study. Results determined that 43% of traced pedigrees carried the champagne gene, 36.1% carried the cream gene, and 20% had pedigrees that were non-informative as these pedigrees went to unknown ancestors or were found to be incorrect as to ancestry. Another 0.9% were determined to be obligate carriers for the cream gene; as the pedigrees presented conflict concerning color designation so that accurate conclusion of coat color phenotype associated with the cream dilution gene could not be verified. Of the 507, all traced back to 6 foundation mares and most of the breed traced back to 2 of these mares; with one mare, Maud, being a champagne mutation and the other, Allens Queen, a cream mutation (Table 1). In conclusion, through pedigree tracing the GASHA origins were documented giving an understanding as to the genetic contributions for today’s GASHA golden coat color. Further, these results will give breeders more input on how they might select for certain coat color phenotypes.

A Comparative Analysis of the Bleeding Profile and Quality of Life Among Women With Hemophilia Genotype Compared to Other Bleeding Disorders.

Introduction Women with bleeding disorders continue to be underdiagnosed as well as undertreated. Women with bleeding disorders include those with genotype for hemophilia (traditionally named hemophilia carriers), von Willebrand disease (VWD), platelet function disorders, and rare bleeding disorders. Among these women, the carriers of hemophilia are usually considered asymptomatic. The present study compares the bleeding profile and quality of life (QOL) of women and girls with hemophilia and compares it to those diagnosed with VWD and rare bleeding disorders. Methods The present study is part of a prospective observational study (August 2023-July 2028) done on women and girls >12 years in two groups. Group 1 was mothers, sisters, or daughters of patients with hemophilia A who were proven carriers. Group 2 was girls and women registered at our center as following bleeding symptoms and diagnosed as either suffering from VWD or rare bleeding disorders. The bleeding profile was assessed by 1:1 interview using the International Society on Thrombosis and Haemostasis (ISTH) Bleeding Assessment Tool (BAT). Health-related QOL (HRQOL) was assessed using the EuroQOL five dimension (EQ5D5L) questionnaire. Results The baseline data collected in the first six months of this prospective study is being presented here. At the time of submission, the center caters to 970 patients with hemophilia and inherited bleeding disorders. Eighty girls (post pubertal) and women with either obligate carrier status for hemophilia (n=68) or a previously diagnosed bleeding disorder (10 VWD, one afibrinogenemia, one factor VII deficiency) were enrolled.The median age of Group 1 was 35 years (25-70 years), whereas that of Group 2 was 15.5 years (13-23 years). In Group 1 (women and girls with hemophilia (WGH)), 58 and 10 were carriers of hemophilia A and B, respectively. Additionally, 83% of WGH had more than one family member with bleeding disorder, whereas 75% of Group 2 had a positive family history. The number of family members with the same disorder ranged from 0-4. Among 68 hemophilia carrier women, 20 reported bleeding symptoms (29.4%), of which 18 reported menorrhagia, one antepartum hemorrhage, and one post-partum hemorrhage and two had joint/muscle bleeds and one each had ENT and gastrointestinal bleeding. Three of them were admitted for treatment of excessive bleeding and treated with plasma/red cells. Three women reported gynecological procedures for excessive bleeding, one was on treatment for ovarian cysts, and four received packed red cells after delivery. The BAT score above 6 was reported only in 10% of WGH. Eighteen patients had undergone a surgical procedure in their life, and three of these women required a transfusion during surgery. Only one woman reported similar complaints in her daughter. The comparative analysis of HRQOL showed a significantly worse score for Group 1 in EQ5D5L domains for pain and anxiety/depression compared to that of Group 2. Conclusions A significant proportion of previously asymptomatic women with hemophilia carrier status were recognized to have significant bleeding tendencies. The QOL of these carriers is comparable to girls with VWD and rare bleeding disorders and requires special attention.

Proactive systematic hemophilia carrier screening: a step toward gender equity in hemophilia care

AbstractDespite numerous efforts to raise awareness, many hemophilia carriers and female persons with hemophilia (PWHs) remain undiagnosed. Between May 2021 and April 2023, we identified potential and obligate carriers of hemophilia A (HA) and hemophilia B (HB) by updating pedigrees of all PWHs followed at the Cliniques universitaires Saint-Luc, Brussels. Retrospective data on previously screened females were collected, including bleeding history, coagulation factor levels, and testing for the proband’s pathogenic variant. In addition, a proactive approach involved sending 125 invitation letters to unscreened or incompletely screened individuals, through related PWHs. In pedigrees of 287 male PWHs (226 HA and 61 HB) and 7 female index patients from 236 families (184 HA and 52 HB), a total of 900 female individuals were identified. Of those, 454 were obligate and/or genetically proven carriers, and 118 were noncarriers. Genetic testing was conducted in 133 obligate, 237 potential, and 4 sporadic carriers, with 190 obligate and 328 potential carriers remaining untested. Among carriers with known factor levels (261/454), 42 HA (23.0%) and 23 HB carriers (29.5%) had a factor level <40 IU/dL. Carriers with a factor deficiency were screened on average 6 years earlier than other females (P = .034). This study, to our knowledge, represents the first systematic effort to identify potential carriers among families of all PWHs within a single center, emphasizing the challenges in comprehensive screening for female individuals genetically linked to one or more PWHs. Such initiatives are vital for achieving equitable access to hemophilia care for all potentially affected individuals, irrespective of gender. This trial was registered at www.ClinicalTrials.gov as #NCT05217992.

Identification and analyses of exonic and copy number variants in spastic paraplegia

Hereditary spastic paraplegias are a diverse group of degenerative disorders that are clinically categorized as isolated; with involvement of lower limb spasticity, or symptomatic, where spastic paraplegia is complicated by further neurological features. We sought to identify the underlying genetic causes of these disorders in the participating patients. Three consanguineous families with multiple affected members were identified by visiting special schools in the Punjab Province. DNA was extracted from blood samples of the participants. Exome sequencing was performed for selected patients from the three families, and the data were filtered to identify rare homozygous variants. ExomeDepth was used for the delineation of the copy number variants. All patients had varying degrees of intellectual disabilities, poor speech development, spasticity, a wide-based gait or an inability to walk and hypertonia. In family RDHR07, a homozygous deletion involving multiple exons and introns of SPG11 (NC000015.9:g.44894055_449028del) was found and correlated with the phenotype of the patients who had spasticity and other complex movement disorders, but not those who exhibited ataxic or indeterminate symptoms as well. In families ANMD03 and RDFA06, a nonsense variant, c.985C > T;(p.Arg329Ter) in DDHD2 and a frameshift insertion‒deletion variant of AP4B1, c.965-967delACTinsC;p.(Tyr322SerfsTer14), were identified which were homozygous in the patients while the obligate carriers in the respective pedigrees were heterozygous. All variants were ultra-rare with none, or very few carriers identified in the public databases. The three loss of function variants are likely to cause nonsense-mediated decay of the respective transcripts. Our research adds to the genetic variability associated with the SPG11 and AP4B1 variants and emphasizes the genetic heterogeneity of hereditary spastic paraplegia.

Retinal Characteristics of Female Choroideremia Carriers: Multimodal Imaging, Microperimetry, and Genetics

PurposeDescribe visual function and retinal features of female carriers of choroideremia (CHM), using multimodal imaging and microperimetry. DesignCross-sectional cohort study Participants and controlsCHM carriers seen in Australia (Melbourne or Perth) or United Kingdom (Oxford or Cambridge) between 2012 and 2023. Healthy age-matched controls seen in Melbourne, Australia, between 2022 and 2023. MethodsParticipants had visual acuity, fundus-tracked microperimetry, optical coherence tomography (OCT), and fundus autofluorescence (FAF) imaging performed. CHM carriers were either genetically and/or clinically confirmed (i.e., obligate carriers). CHM carriers were grouped according to their retinal phenotype and compared to healthy controls. Statistical analyses were performed on StataBE (v18.0). Main outcome measuresBest-corrected visual acuity (BCVA), low-luminance visual acuity (LLVA), average retinal sensitivity, volume of macular hill of vision (HoV), inner retinal thickness (IRT), and photoreceptor complex (PRC) thickness. ResultsEighty-six eyes of 43 CHM carriers and 60 eyes of 30 healthy controls were examined using multimodal imaging and microperimetry. Median age was 54 and 48.5 years for CHM carriers and controls, respectively (p=0.18). Most CHM carriers (86%) were genetically confirmed. CHM carriers and controls had strong inter-eye correlation between eyes for BCVA and average retinal sensitivity (p<0.001). LLVA and macular HoV tests were sensitive tests to detect changes in CHM carriers with mild phenotypes (i.e., fine and coarse). CHM carriers with geographic and/or male pattern phenotypes had reduced BCVA, LLVA, retinal sensitivity, and retinal thinning, compared to healthy controls. Retinal thickening of the inner retina was observed in the central 1 degree, despite generalised thinning of the PRC in the central 7 degrees, indicating retinal remodelling in CHM carriers, compared to controls. There were no genotype-phenotype correlations observed. ConclusionsFemale carriers of CHM with severe retinal phenotypes (i.e., geographic or male pattern) have significantly decreased visual function and retinal structural changes, when compared to age-matched controls and those carriers with milder phenotypes. LLVA and volumetric measures of the macular HoV were found to be the most sensitive functional tests to detect milder retinal disease (fine and coarse phenotypes) in CHM carriers.

Rare within Rare: A Girl with Severe Haemophilia A and Turner Syndrome

A coincidental occurrence of severe haemophilia A and Turner syndrome in a female person is extremely rare (less than 10 cases published). In such challenging cases, a multidisciplinary approach based on medicine of precision with full access to genetic and bio-molecular exploration is indispensable. The article presents an eight-year-old girl, with a family history of haemophilia, without significant disease signs (only post-dental extraction bleeding and a shorter stature). Discordantly, however, the investigations revealed a challenging condition: a genotype of 46,X,i(Xq), with an Isochromosome Xq responsible for the Turner syndrome and simultaneously, for the detrimental transformation, interfering with X chromosome inactivation, of an obligate hemophilia carrier into a severe hemophilia case—two distinct and provocative diseases.

Proactive Systematic Hemophilia Carrier Screening: A Step Towards Gender Equity in Hemophilia Care

Introduction Despite multiple awareness-raising initiatives, and in contrast with male persons with hemophilia (PwH), a considerable number of carriers and female PwH still go undiagnosed. We here present the findings of a proactive and extensive hemophilia carrier screening project. Methods From May 2021 until April 2023, potential and obligate carriers of hemophilia A (HA) and B (HB) were identified by updating family trees of all PwH regularly followed at the Cliniques universitaires Saint-Luc. Data from previously screened female individuals (bleeding history, coagulation factor assays and testing for the index patient's pathological genetic variant) were collected retrospectively through electronic medical records (EMRs). Female individuals who had not been previously screened or with missing data were provided with a total of 125 invitation letters by related index hemophilia patients. The study protocol received approval of the local ethics committee. Results All 287 male PwH (226 HA, 61 HB) from 228 families (180 HA, 48 HB) were included in the analysis. Seven female PwH (3 HA, 4 HB) were considered as index cases in their families. In total, based on the family trees, there were 900 females, among which 454 were obligate and/or genetically proven carriers of hemophilia and 118 were found to be non-carriers (Figure 1). Mean age at diagnosis was 30.7 years (range 1-82) in families with HA and 30.1 years (range 0.5-93) in families with HB, without significant difference between these two groups (p=0.809) or between families with severe, moderate or mild hemophilia (p=0.535). Genetic testing for pathological variants has been conducted in 133 obligate, 237 potential and 4 sporadic carriers, and remains to be performed in 190 obligate and 328 potential carriers. Eight females were obligate non-carriers. The group of mothers, sisters and daughters of PwH comprised 543 females, of which at least 178 (35.7% of those with known date of birth) were of reproductive age (18-49 years). Seventy-three percent of females in the latter group have had genetic testing. The proportion of female individuals genetically tested did not significantly differ between families of different severities of HA (p=0.132). In families with moderate HB, female individuals were more likely to be tested (genetic status known in 59.4%) than in other HB severity groups (p=0.01), yet this may be attributed to the presence of one large family comprising 6 male persons with moderate HB and 22 female individuals, of whom a large proportion (n=18, 82%) has had genetic testing. Among carriers with known coagulation factor levels (261/454), 42 (23.0%) and 23 (29.5%) carriers of HA and HB, respectively, had a factor level below 40 IU/dL, and 65 (35.5 %) and 32 (41.0%) had a factor level below 50 IU/dL. The proportion of carriers with a factor level below 40 IU/dL did not significantly differ between families with severe, moderate and mild hemophilia (22.6%, 34.7% and 22.7% respectively, p=0.213), neither did mean coagulation factor levels in carriers with a factor deficiency in these groups (26.2, 30.4 and 27.1 IU/dL in families with severe, moderate and mild HA and HB, p=0.344). Carriers with a coagulation factor deficiency of less than 40 IU/dL were screened earlier than other female individuals (mean age at diagnosis 25.8 and 31.8 years, respectively, p=0.034). Conclusions This study represents the first reported attempt to systematically identify all (potential) hemophilia carriers within families of all PwH followed at a single hemophilia treatment center. To date, this initiative has allowed 44% of the entire cohort to be screened, and carrier status to be genetically confirmed in 73% of mothers, sisters and daughters of PwH who are of childbearing age, based on the date of birth documented in their EMR. Although original and promising, these data reflect the major challenges and difficulties in reaching out and providing appropriate screening to all women genetically linked to one or more PwH. The carrier screening efforts that have been initiated in our center, and which should ideally be replicated across the hemophilia community globally, appear as a critical step towards providing equal access to haemophilia diagnosis and care to all potentially affected individuals, regardless of their gender.

RP2-Associated X-linked Retinopathy: Clinical Findings, Molecular Genetics, and Natural History in a Large Cohort of Female Carriers

RP2-associated retinopathy typically causes severe early onset retinitis pigmentosa (RP) in affected males. However, there is a scarcity of reports describing the clinical phenotype of female carriers. We tested the hypothesis that RP2 variants manifest in female carriers with a range of functional and anatomic characteristics. Retrospective case series. Females with disease-causing variants in RP2 were identified from investigation of pedigrees affected by RP2 retinopathy. All case notes and results of molecular genetic testing, retinal imaging (fundus autofluorescence imaging, optical coherence tomography (OCT)), and electrophysiology were reviewed. Forty pedigrees were investigated. Twenty-nine pedigrees had obligate carriers or molecularly confirmed female members with recorded relevant history and/or examination. For 8 pedigrees, data were available only from history, with patients reporting affected female relatives with RP in 4 cases and unaffected female relatives in the other 4 cases. Twenty-seven females from 21 pedigrees were examined by a retinal genetics specialist. Twenty-three patients (85%) reported no complaints and had normal vision and 4 patients had RP-associated complaints (15%). Eight patients had normal fundus examination (30%), 10 had a tapetal-like reflex (TLR; 37%), 5 had scattered peripheral pigmentation (19%), and the 4 symptomatic patients had fundus findings compatible with RP (15%). All asymptomatic patients with normal fundus, TLR, or asymptomatic pigmentary changes had a continuous ellipsoid zone on OCT when available. The electroretinograms revealed mild to severe photoreceptor dysfunction in 9 of 11 subjects, often asymmetrical, including 5 with pattern electroretinogram evidence of symmetrical (n = 4) or unilateral (n = 1 subject) macular dysfunction. Most carriers were asymptomatic, exhibiting subclinical characteristics such as TLR and pigmentary changes. However, female carriers of RP2 variants can manifest RP. Family history of affected females with RP does not exclude X-linked disease. The phenotypic spectrum as described herein has prognostic and counselling implications for RP2 carriers and patients.

Unveiling genetics of non-syndromic albinism using whole exome sequencing: A comprehensive study of TYR, TYRP1, OCA2 and MC1R genes in 17 families

BackgroundOculocutaneous albinism (OCA) is a group of skin depigmentation disorders. Clinical presentation of OCA includes defects in melanocyte differentiation, melanin biosynthesis, and melanosome maturation and transport. ObjectivesA molecular diagnostics study of families presenting oculocutaneous albinism. MethodsIn this study, 17 consanguineous OCA families consisting of 93 patients were investigated. Whole Exome Sequencing (WES) of the index patient in each family were performed. Short listed variants of WES were Sanger validated for Mendelian segregation in obligate carriers and other available family members. Variant prioritization and pathogenicity were classified as per the criteria of American College Medical Genetics and Genomics (ACMG). Comparative computational modelling was performed to predict the potential damaging effect of the altered proteins. Results15 pathogenic variations: c.132 T > A, c.346C > T, c.488C > G, c.1037G > A in TYR, c.1211C > T, c.1441G > A, c.1706_1707insT, c.2020C > G, c.2402G > C, c.2430del, in OCA2, c.1067G > A in TYRP1 and c.451C > T, c.515G > T, c.766C > T, c.917G > A in MC1R genes were identified. Three variants in OCA2 gene were characterized: c.1706_1707insT, c.2430del, and c.2402G > C, all of which were not reported before in OCA families. ConclusionA few studies focusing on mutation screening of OCA patients have been reported before; however, this study has uniquely presents the Pakhtun ethnic population residing on the North-Western boarder. It explains that TYR, OCA2, TYRP1, and MC1R variations lead to non-syndromic OCA phenotype The overlapping phenotypes of OCA can precisely be diagnosed for its molecular pathogenicity using WES. This study recommends WES as a first-line molecular diagnostic tool, and provides a basis for developing customized genetic tests i.e. pre-marital screening to reduce the disease burden in the future generations.

Prevalence of Congenital Color Vision Deficiency in Southern Taiwan and Detection of Female Carriers by Visual Pigment Gene Analysis.

This study aimed to investigate the prevalence of color vision deficiencies (CVDs) and determine whether carriers could be detected by analyzing the visual pigment genes. Materials and Methods: The data of students who underwent routine CVD screening using the Ishihara color test in Kaohsiung, Southern Taiwan were analyzed. Furthermore, the DNA samples of 80 randomly selected females and four obligate carriers were analyzed. The most upstream genes, downstream genes, and the most downstream genes in the red/green pigment gene arrays were amplified separately using polymerase chain reaction (PCR), and exon 5 of each gene was analyzed. The prevalence of congenital red-green CVD in this study was 3.46% in males and 0.14% in females. The PCR analysis of the first gene, downstream gene, and last gene revealed normal patterns in 73 normal cases. Seven unusual patterns were detected in two proton carriers and five deutan carriers. Among the randomly selected females, 8.8% (7/80) were CVD carriers. The prevalence of CVD among male Taiwanese students in this study was 3.46%. Female carriers of congenital CVD can be identified by molecular analysis of the visual pigment genes. The proportion of CVD carriers among the randomly selected females was 8.8%, which was slightly higher than expected and further studies are warranted.

Potential Founder Variants in COL4A4 Identified in Bukharian Jews Linked to Autosomal Dominant and Autosomal Recessive Alport Syndrome.

Alport syndrome is a hereditary disorder caused by pathogenic variants in the COL4A gene, which can be inherited in an autosomal recessive, dominant, or X-linked pattern. In the Bukharian Jewish population, no founder pathogenic variant has been reported in COL4A4. The cohort included 38 patients from 22 Bukharian Jewish families with suspected Alport syndrome who were referred the nephrogenetics clinic between 2012 and 2022. The study collected demographic, clinical, and genetic data from electronic medical records, which were used to evaluate the molecular basis of the disease using Sanger sequencing, and next-generation sequencing. Molecular diagnosis was confirmed in 20/38 patients, with each patient having at least one of the three disease-causing COL4A4 variants detected: c.338G<A (p.Gly113Asp), c.3022G>A (p.Gly1008Arg), and c.871-6T>C. In addition, two patients were obligate carriers. Overall, there were 17 heterozygotes, 2 compound heterozygotes, and 3 homozygotes. Each variant was detected in more than one unrelated family. All patients had hematuria with/without proteinuria at referral, and the youngest patient with proteinuria (age 5 years) was homozygous for the c.338G>A variant. End-stage renal disease was diagnosed in two patients at the age of 38 years, a compound heterozygote for c.338G>A and c.871-6T>C. Hearing deterioration was detected in three patients, the youngest aged 40 years, all of whom were heterozygous for c.338G>A. This study unveils three novel disease-causing variants, c.3022G>A, c.871-6T>C, and c.338G>A, in the COL4A4 gene that are recurrent among Jews of Bukharian ancestry, and cause Alport syndrome in both dominant and recessive autosomal inheritance patterns.

Germline EGFR Mutations and Familial Lung Cancer.

The genomic underpinnings of inherited lung cancer risk are poorly understood. This prospective study characterized the clinical phenotype of patients and families with germline EGFR pathogenic variants (PVs). The Investigating Hereditary Risk from T790M study (ClinicalTrials.gov identifier: NCT01754025) enrolled patients with lung cancer whose tumor profiling harbored possible germline EGFR PVs and their relatives, either in person or remotely, providing germline testing and follow-up. A total of 141 participants were enrolled over a 5-year period, 100 (71%) remotely. Based upon previous genotyping, 116 participants from 59 kindreds were tested for EGFR T790M, demonstrating a pattern of Mendelian inheritance with variable lung cancer penetrance. In confirmed or obligate carriers of a germline EGFR PV from 39 different kindreds, 50/91 (55%) were affected with lung cancer with 34/65 (52%) diagnosed by age 60 years. Somatic testing of lung cancers in carriers revealed that 35 of 37 (95%) had an EGFR driver comutation. Among 36 germline carriers without a cancer diagnosis, 15 had computed tomography (CT) imaging and nine had lung nodules, including a 28-year-old with >10 lung nodules. Given geographic enrichment of germline EGFR T790M in the southeast United States, genome-wide haplotyping of 46 germline carriers was performed and identified a 4.1-Mb haplotype shared by 41 (89%), estimated to originate 223-279 years ago. To our knowledge, this is the first prospective description of familial EGFR-mutant lung cancer, identifying a recent founder germline EGFR T790M variant enriched in the Southeast United States. The high prevalence of EGFR-driver lung adenocarcinomas and lung nodules in germline carriers supports effort to identify affected patients and family members for investigation of CT-based screening for these high-risk individuals.

Discordant Staining Patterns and Microsatellite Results in Tumors of MSH6 Pathogenic Variant Carriers

Diagnosis of Lynch syndrome (LS) caused by a pathogenic germline MSH6 variant may be complicated by discordant immunohistochemistry (IHC) and/or by a microsatellite stable (MSS) phenotype. This study aimed to identify the various causes of the discordant phenotypes of colorectal cancer (CRC) and endometrial cancer (EC) in MSH6-associated LS. Data were collected from Dutch family cancer clinics. Carriers of a (likely) pathogenic MSH6 variant diagnosed with CRC or EC were categorized based on an microsatellite instability (MSI)/IHC test outcome that might fail to result in a diagnosis of LS (eg, retained staining of all 4 mismatch repair proteins, with or without an MSS phenotype, and other staining patterns). When tumor tissue was available, MSI and/or IHC were repeated. Next-generation sequencing (NGS) was performed in cases with discordant staining patterns. Data were obtained from 360 families with 1763 (obligate) carriers. MSH6 variant carriers with CRC or EC (n = 590) were included, consisting of 418 CRCs and 232 ECs. Discordant staining was reported in 77 cases (36% of MSI/IHC results). Twelve patients gave informed consent for further analysis of tumor material. Upon revision, 2 out of 3 MSI/IHC cases were found to be concordant with the MSH6 variant, and NGS showed that 4 discordant IHC results were sporadic rather than LS-associated tumors. In 1 case, somatic events explained the discordant phenotype. The use of reflex IHC mismatch repair testing, the current standard in most Western countries, may lead to the misdiagnosis of germline MSH6 variant carriers. The pathologist should point out that further diagnostics for inheritable colon cancer, including LS, should be considered in case of a strong positive family history. Germline DNA analysis of the mismatch repair genes, preferably as part of a larger gene panel, should therefore be considered in potential LS patients.

Lorpucitinib (JNJ-64251330) in patients with familial adenomatous polyposis (FAP): Results from a phase 1b study.

10514 Background: FAP is the most common hereditary adenomatous polyposis syndrome and, if left untreated, will lead to colorectal cancer development in nearly all patients. Chronic inflammation, driven in part by the Janus kinase (JAK)/signal transducer and activator of transcription (STAT) pathway, may promote polyp formation. Enteric-selective inhibition of the JAK/STAT pathway may provide a treatment for FAP. Lorpucitinib is an oral, small molecule, potent pan-JAK inhibitor with favorable enteric-selective properties. Here, we report the efficacy, safety, and pharmacokinetic (PK) results from a phase 1b study of lorpucitinib in patients with FAP (NCT05014360). Methods: Patients aged ≥18 years with ≥6 polyps ≥2 mm in diameter in the rectum or colon with FAP ( APC germline mutation or obligate carrier) received lorpucitinib 75 mg twice daily for 24 weeks. The primary objective was to evaluate the effect of lorpucitinib on colorectal polyp burden at Week 24, assessed by endoscopy at baseline and Week 24. Secondary objectives were safety, PK, and biomarker assessments of lorpucitinib activity. Results: Overall, 42 (23 pre-colectomy; 19 post-colectomy) patients with FAP were enrolled, with a median age of 33 (range, 19-61) years. No clear effect on polyp burden was observed at Week 24. Gut mucosal and polyp concentrations of lorpucitinib were much higher than plasma concentrations, indicating an enteric-selective distribution. Mean sigmoid colon, rectum, and polyp concentrations of lorpucitinib at Week 8 were 112-, 473-, and 108-fold higher, respectively, than the observed maximum plasma concentration at Week 8 (1 hour). At Week 8, lorpucitinib achieved JAK tyrosine kinase inhibition in mucosal biopsies as evidenced by a median 37% reduction in normalized pSTAT-3 levels. Lorpucitinib reduced serum-based inflammatory biomarkers such as C-reactive protein and serum amyloid A by Week 16 of therapy. Some patients reported an improvement of clinical symptoms such as less frequent bowel movements and less blood in the stool. The most common adverse events (AEs) were abdominal pain (16%), bilirubin increased (13%), headache (13%), lipase increased (13%), and diarrhea (13%). There were no treatment-related serious AEs, grade 3 treatment-emergent AEs, serious infections, or venous thromboembolisms. Conclusions: These results show that lorpucitinib had no clear effect on polyp burden. The study found that lorpucitinib is safe and exhibits an enteric-selective distribution in FAP patients. Inhibition of JAK tyrosine kinase signaling was associated with reduced STAT-3 phosphorylation in mucosal biopsies from FAP patients. While reductions observed in polyp burden were not clinically significant, lorpucitinib treatment lowered levels of several serum inflammatory biomarkers. Treatment with lorpucitinib was safe and well tolerated, and may improve clinical symptoms associated with FAP. Clinical trial information: NCT05014360 .

46 Pedigree tracing to determine origins of the Palomino Horse Breeders of America stock-type horse

Registration numbers for the Palomino Horse Breeders of America (PHBA) have risen over the years due in part to new registration guidelines. In fact, PHBA has recently changed registration guidelines allowing registration of any horse with a palomino body color including those with unknown pedigrees. While this trend promotes registry growth, pedigree tracing can assist in documenting breed origins. Pedigree tracing is particularly valuable for color registries as the study of coat color patterns is a relatively new science plagued with misunderstandings due to pedigrees with inaccurate color designations. The objective of this study was to develop a better understanding of the historical origins of today's PHBA stock-type horse through pedigree tracing. 800 horses were randomly sampled from published entries from 10 years of the PHBA World Show. Only 460 of the 800 samples were utilized for this study due to the lack of verified documentation of extended pedigrees that included documented coat colors taken from the All-Breed Database. A complete record was defined as having an uninterrupted generation to generation inheritance pattern of a cream dilution gene influenced coat color from the sampled individual that directly traces back to the earliest existing recorded relative. Results indicate that a small number of foundation sires (Table 1) are responsible for the modern PHBA stock-type horse. The majority of horses within the Hall of Fame have pedigrees that trace back to only one of the sires identified in this study. Two of the identified sires have conflictsconcerning color designation and can be only identified as obligate cream gene carriers. While this study assists in documenting the origins of the breed, as PHBA continues to grow, additional genetic testing to accurately identify the cream gene within the horses registered may further support the goals of a color registry that is based upon horses with a cream phenotype.

Immunoreactive Trypsinogen Levels in Infants Born to Women with Cystic Fibrosis Taking Elexacaftor-Tezacaftor-Ivacaftor

Background/Objective:Cystic Fibrosis (CF) is a lethal autosomal recessive disease caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene affecting people of every race and ethnicity in the US. Highly effective modulator therapies (HEMT), such as elexacaftor-tezacaftor-ivacaftor (ETI), correct misfolding and/or improve functioning of the abnormal CFTR protein to lessen disease severity. Most people with CF are diagnosed following abnormal newborn screening (NBS), which involves measuring levels of immunoreactive trypsinogen (IRT). There have been case reports of falsely low IRT levels among infants with CF exposed to ETI in utero, but an overall assessment of IRT levels among these infants has not been conducted. We hypothesize that infants born to mothers with CF taking ETI (ETI-exposed) may have lower IRT levels than newborns with CF, CFTR-related metabolic syndrome (CRMS), or CF carriers.Methods:NBS data from infants born between 2020-22 in Indiana with at least one CFTR mutation were collected and compared to infants born to mothers with CF taking ETI followed at Indiana University, regardless of CFTR mutation status. Infants were categorized as: CF, CRMS, Carrier, ETI-exposed, and Unknown (i.e., diagnosis not determined). An ANOVA test was performed on log-transformed data, with p-values adjusted for Dunnett’s to compare IRT levels of infant groups to ETI-exposed group.Results:There were 51 children with CF, 21 with CRMS, 489 CF carriers, and 19 ETI-exposed infants. Compared to other groups, ETI-exposed infants had a lower median IRT value and IQR (p&lt;0.0001). To our knowledge, there are no CF diagnoses among ETI-exposed infants.Conclusion:IRT levels for ETI-exposed infants, who are obligate CF carriers, were lower than for other infants with CF-related diagnoses, raising the likelihood of false normal NBS results. ETI-exposed infants should have CFTR mutation analysis performed to correctly categorize them as CF, CRMS, or CF carriers.

Fetal akinesia deformation sequence syndrome associated with recessive TTN variants.

Arthrogryposis multiplex congenita (AMC) [also known as multiple joints contracture or Fetal Akinesia Deformation Sequence (FADS)] is etiologically a heterogeneous condition with an estimated incidence of approximately 1 in 3000 live births and much higher incidence when prenatally diagnosed cases are included. The condition can be acquired or secondary to fetal exposures and can also be caused by a variety of single-gene disorders affecting the brain, spinal cord, peripheral nerves, neuromuscular junction, muscle, and a variety of disorders affecting the connective tissues (Niles et al., Prenatal Diagnosis, 2019; 39:720-731). The introduction of next-generation gene sequencing uncovered many genes and causative variants of AMC but also identified genes that cause both dominant and recessive inherited conditions with the variability of clinical manifestations depending on the genes and variants. Molecular diagnosis in these cases is not only important for prognostication but also for the determination of recurrence risk and for providing reproductive options including preimplantation and prenatal diagnosis. TTN, the largest known gene in the human genome, has been known to be associated with autosomal dominant dilated cardiomyopathy. However, homozygote and compound heterozygote pathogenic variants with recessive inheritance have rarely been reported. We report the effect of recessive variants located within the fetal IC and/or N2BA isoforms in association with severe FADS in three families. All parents were healthy obligate carriers and none of them had cardiac or skeletal muscle abnormalities. This report solidifies FADS as an alternative phenotypic presentation associated with homozygote/compound heterozygous pathogenic variants in the TTN.