Heterozygous Patients Research Articles

Compound Heterozygosis in AADC Deficiency and Its Complex Phenotype in Terms of AADC Protein Population.

Aromatic amino acid decarboxylase (AADC) deficiency is a rare monogenic disease due to mutations in the ddc gene producing AADC, a homodimeric pyridoxal 5′-phosphate-dependent enzyme. The disorder is often fatal in the first decade and is characterized by profound motor impairments and developmental delay. In the last two years, there has been a net rise in the number of patients and variants identified, maybe also pushed by the ongoing gene therapy trials. The majority of the identified genotypes are compound heterozygous (about 70%). Efforts are underway to reach early diagnosis, find possible new markers/new fast methods, and predict clinical outcome. However, no clear correlation of genotype-to-phenotype exists to date. Nevertheless, for homozygous patients, reliable results have been obtained using genetic methods combined with available computational tools on crystal structures corroborated by biochemical investigations on recombinant homodimeric AADC variants that have been obtained and characterized in solution. For these variants, the molecular basis for the defect has been suggested and validated, since it correlates quite well with mildness/severity of the homozygous phenotype. Instead, prediction for compound heterozygous patients is more difficult since complementation effects could happen. Here, by analyzing the existing literature on compound heterozygosity in AADC deficiency and other genetic disorders, we highlight that, in order to assess pathogenicity, the measurement of activity of the AADC heterodimeric variant should be integrated by bioinformatic, structural, and functional data on the whole protein constellation theoretically present in such patients. A wider discussion on symptomatic heterozygosity in AADC deficiency is also presented.

Skewed X-Chromosome Inactivation and Parental Gonadal Mosaicism Are Implicated in X-Linked Recessive Female Hemophilia Patients.

Background: Hemophilia A (HA) and B (HB) are X-linked recessive disorders that mainly affect males born from a mother carrier. Females are rarely affected but a number of mechanisms have been suggested in symptomatic females, such as skewed X-chromosome inactivation (XCI), chromosomal rearrangements, and hermaphrodites. Different methodologies are required to elucidate the underlying causes of such diseases in female patients. Methods: Three families with female hemophilia patients, including two HA and one HB, were enrolled for genetic analyses. Cytogenetics, molecular examinations on F8 and F9 genes, XCI assay, and linkage analysis were performed. Results: All three female patients are demonstrated to be heterozygous for an F8, or F9 mutation: one patient is inherited from her unaffected mother and the other two are sporadic cases. All three patients exhibit skewed XCI. The inherited patient is found to be unmethylated in the maternal X chromosome, which increases the potential for the expression of the mutant allele. The two sporadic cases are hypomethylated or unmethylated in the paternal X chromosome, suggesting that paternal gonadal mosaicism may exist in these families. Conclusions: In addition to screening for coagulation function, different genetic analyses are mandatory to explore the nature of mechanisms responsible for the X-linked recessive disorders in female patients as shown in this study. Our results confirm that skewed XCI is responsible for hemophilia in heterozygous female patients. Likewise, our results implicate that parental gonadal mosaicism, followed by skewed XCI, contributes to hemophilia in “sporadic” female patients.

Novel Germline TET2 Mutations in Two Unrelated Patients with Autoimmune Lymphoproliferative Syndrome-Like Phenotype and Hematologic Malignancy.

Somatic mutations in the ten-eleven translocation methylcytosine dioxygenase 2 gene (TET2) have been associated to hematologic malignancies. More recently, biallelic, and monoallelic germline mutations conferring susceptibility to lymphoid and myeloid cancer have been described. We report two unrelated autoimmune lymphoproliferative syndrome-like patients who presented with T-cell lymphoma associated with novel germline biallelic or monoallelic mutations in the TET2 gene. Both patients presented a history of chronic lymphoproliferation with lymphadenopathies and splenomegaly, cytopenias, and immune dysregulation. We identified the first compound heterozygous patient for TET2 mutations (P1) and the first ALPS-like patient with a monoallelic TET2 mutation (P2). P1 had the most severe form of autosomal recessive disease due to TET2 loss of function resulting in absent TET2 expression and profound increase in DNA methylation. Additionally, the immunophenotype showed some alterations in innate and adaptive immune system as inverted myeloid/plasmacytoid dendritic cells ratio, elevated terminally differentiated effector memory CD8 + T-cells re-expressing CD45RA, regulatory T-cells, and Th2 circulating follicular T-cells. Double-negative T-cells, vitamin B12, and IL-10 were elevated according to the ALPS-like suspicion. Interestingly, the healthy P1's brother carried a TET2 mutation and presented some markers of immune dysregulation. P2 showed elevated vitamin B12, hypergammaglobulinemia, and decreased HDL levels. Therefore, novel molecular defects in TET2 confirm and expand both clinical and immunological phenotype, contributing to a better knowledge of the bridge between cancer and immunity.

Mosaicism in Tumor Suppressor Gene Syndromes: Prevalence, Diagnostic Strategies, and Transmission Risk.

A mosaic state arises when pathogenic variants are acquired in certain cell lineages during postzygotic development, and mosaic individuals may present with a generalized or localized phenotype. Here, we review the current state of knowledge regarding mosaicism for eight common tumor suppressor genes-NF1, NF2, TSC1, TSC2, PTEN, VHL, RB1, and TP53-and their related genetic syndromes/entities. We compare and discuss approaches for comprehensive diagnostic genetic testing, the spectrum of variant allele frequency, and disease severity. We also review affected individuals who have no mutation identified after conventional genetic analysis, as well as genotype-phenotype correlations and transmission risk for each tumor suppressor gene in full heterozygous and mosaic patients. This review provides new insight into similarities as well as marked differences regarding the appreciation of mosaicism in these tumor suppressor syndromes.

Generation of human induced pluripotential stem cells from individuals with complex heterozygous, isogenic corrected, and homozygous Bloc1s1 mutations

Genetic studies show that BLOC1S1 modulates mitochondrial and endosome-lysosome function (Wu et al., 2021a). Furthermore, Bloc1s1 mutations are linked to leukodystrophy (Bertoli-Avella et al., 2021). The Vanderver laboratory identified additional individuals with leukodystrophy that harbored either complex heterozygous (Bloc1s1 c.206A > C and c.359G > A), or homozygous (Bloc1s1 c.185 T > C) point mutations. We generated induced pluripotential stem cell (iPSC) lines from these subjects, from parents of the complex heterozygous mutations patient, and from CRISPR isogenic (c.206A > C and c.359G > A) corrected iPSC-line. These complex heterozygous, homozygous, and isogenic-corrected Bloc1s1 lines were phenotypically normal and were capable of differentiation towards the three germ layers.

A Severe Form of Familial Desminopathy Due to a Homozygous Nonsense DES Variant in Two Siblings.

Familial primary desminopathies are usually autosomal dominantly inherited and present at the age of 20 to 40 years with progressive muscle weakness and atrophy, cardiomyopathy, and cardiac arrhythmias. Cardiac features may precede the muscular weakness. Here, we report the rare case of two siblings presenting with a desminopathy at pediatric age, due to homozygous nonsense variations (c.700G > T [p.Glu234Ter]) in DES, representing an autosomal recessive inheritance pattern. The homozygous state of these variants is expected to result in the complete absence of desmin production. Rare autosomal recessive DES variants are associated with an earlier clinical presentation (from childhood to early adulthood) and faster evolution compared with more common autosomal dominant variants. A normal resting electrocardiography (ECG) and cardiac ultrasound can be a pitfall, as seen in our patient who has extensive fibrotic scarring on cardiac magnetic resonance imaging (MRI). We recommend yearly cardiac ultrasound, yearly 24-hour Holter monitoring and 2 yearly cardiac MRI from the age of 10 years in all asymptomatic patients. Heterozygous patients usually have no or only mild complaints but, though not yet reported in autosomal recessive desminopathies, muscular complaints are possible, as seen in the father of our patients. The prognosis for these patients with desminopathy presenting in childhood is unpredictable but anticipated as poor.

Heterozygous E148Q Mutation in an Indian Family with a Milder Form of Familial Mediterranean Fever

Dear Editor, Familial Mediterranean fever (FMF, OMIM no. 249100) is an inherited autoinflammatory disorder resulting from MEFV gene mutations. A 15-year-old girl from Kerala, South India, born of a nonconsanguineous union presented with recurrent fever, diffuse abdominal pain, and left knee joint pain for 1 year. She had fever for 3 days every week associated with left knee arthritis. Some of the episodes were associated with diffuse abdominal pain, oral ulcers, and an erythematous facial rash. She also had right hip and ankle pain with swelling on a few occasions. On examination, she had swollen and warm left knee joint. Her 12-year-old sibling also had similar problems (recurrent fever, diffuse abdominal pain, and joint pain) for 10 months. Both the parents were asymptomatic. Blood tests showed neutrophilic leukocytosis, high erythrocyte sedimentation rate, and C-reactive protein. Ultrasonography of the abdomen showed mild ascites. Immunological testing showed normal C3 complement and the absence of rheumatoid factor, antinuclear, anti-double-stranded DNA, and anti-neutrophilic cytoplasmic antibodies. The periodicity of symptoms and positive family history made us consider inherited autoinflammatory disorder. Targeted mutational analysis showed the MEFV variant E148Q in the heterozygous state in both siblings. No pathogenic variants were identified in the MEFV exon, TNFRSF1A, and MVK genes [Table 1]. The patient and her younger sister were managed with colchicine (1.0 mg daily), and on follow-up up to 1 year, the patients were asymptomatic. Genetic counseling was given to the patient family.Table 1: The results of targeted mutational analysis of the MEFV, TNFRSF1A, and MVK genes in the two siblingsFMF is common among certain ethnic groups of the Eastern Mediterranean region. More than 300 different mutations of the MEFV gene related to FMF have been identified, although only a few are pathogenic.[1] Previous studies testing the pathogenicity of E148Q alteration showed conflicting results. In a study of 646 FMF patients by Tirosh et al., 1% had a heterozygous E148Q variant with a milder clinical phenotype compared with patients having M694V homozygosity.[2] A Turkish FMF cohort of 153 patients had 33 (21.6%) patients with E148Q variant and 34 compound heterozygous patients (with E148Q and exon 10 mutations).[3] E148Q allele frequency among FMF patients was found to be 25% in Jewish, Arab, and Druze patients living in Israel, 20% in Turkish, 34% in Japanese, 17% in Azeri Turk patients living in Iran, and 2% in Armenian patients.[3] Several studies noted that the E148Q mutation was associated with a milder FMF phenotype. However, there was no significant difference in the frequency of clinical findings among the Turkish cohort.[3] Two patients from a South Indian family with recurrent fever, diffuse abdominal pain, and left knee joint pain for 1 year were found to have the MEFV variant E148Q in the heterozygous state. Both of them responded well to colchicine. The diagnosis of a milder phenotype of FMF was thus confirmed. Even though autoinflammatory disorders were reported from the Indian subcontinent,[4,5] we do not have data regarding the E148Q allele frequency and other mutations causing FMF. We report FMF in two members of a family with E148Q mutation which was not previously reported from the Indian subcontinent. This case reminds the readers to consider hereditary periodic fever syndromes when evaluating recurrent fever and the importance of E148Q mutation in the Indian population. Ethics approval All procedures performed in studies involving human participants were by the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. Declaration of patient consent The authors certify that informed consent was taken from the father of both patients and assent was obtained from the children for participating in the study. The informed consent from the father and assent from the children were also obtained for using the clinical information to be reported in the journal. The patients and parents understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.

Systemic vasculopathy associated with an RNF213 p.Arg4810Lys variant in moyamoya disease: A review

Moyamoya disease (MMD) is a steno-occlusive disease of the distal cerebral arteries. Ring finger protein 213 (RNF213) p.Arg4810Lys is a susceptibility gene of MMD for which related vasculopathies are not well characterized. Heterozygous patients were mostly asymptomatic or exhibited isolated MMD. Homozygous patients showed a very unique pattern of diffuse narrowing of the entire aorta along with stenosis of the splanchnic, renal, coronary, iliofemoral, and/or peripheral pulmonary arteries, regardless of presence or absence of MMD. RNF213 p.Arg4810Lys is associated with high penetrance of systemic vasculopathy in homozygous patients and low penetrance of intracranial stenosis, i.e., MMD, in heterozygous patients, which suggests a gene-dosage effect.

Patient-Derived iPSCs Reveal Evidence of Telomere Instability and DNA Repair Deficiency in Coats Plus Syndrome.

Coats plus (CP) syndrome is an inherited autosomal recessive condition that results from mutations in the conserved telomere maintenance component 1 gene (CTC1). The CTC1 protein functions as a part of the CST protein complex, a protein heterotrimer consisting of CTC1–STN1–TEN1 which promotes telomere DNA synthesis and inhibits telomerase-mediated telomere elongation. However, it is unclear how CTC1 mutations may have an effect on telomere structure and function. For that purpose, we established the very first induced pluripotent stem cell lines (iPSCs) from a compound heterozygous patient with CP carrying deleterious mutations in both alleles of CTC1. Telomere dysfunction and chromosomal instability were assessed in both circulating lymphocytes and iPSCs from the patient and from healthy controls of similar age. The circulating lymphocytes and iPSCs from the CP patient were characterized by their higher telomere length heterogeneity and telomere aberrations compared to those in control cells from healthy donors. Moreover, in contrast to iPSCs from healthy controls, the high levels of telomerase were associated with activation of the alternative lengthening of telomere (ALT) pathway in CP-iPSCs. This was accompanied by inappropriate activation of the DNA repair proteins γH2AX, 53BP1, and ATM, as well as with accumulation of DNA damage, micronuclei, and anaphase bridges. CP-iPSCs presented features of cellular senescence and increased radiation sensitivity. Clonal dicentric chromosomes were identified only in CP-iPSCs after exposure to radiation, thus mirroring the role of telomere dysfunction in their formation. These data demonstrate that iPSCs derived from CP patients can be used as a model system for molecular studies of the CP syndrome and underscores the complexity of telomere dysfunction associated with the defect of DNA repair machinery in the CP syndrome.

Phenotypic polymorphism in Wilson’s disease – between genetics and epigenetics

Background: Wilson’s disease is a rare, autosomal recessive genetic disorder that affects the biliary excretion of copper and its toxic accumulation in various tissues, especially the liver and brain. It is widespread throughout the world, with a high prevalence in socio-culturally isolated communities. The course of the disease and the age of onset depend on the site of mutation in the gene and the degree of functional impairment of the ATP7B protein. The presence of the compound heterozygous patient complicates the comparative genetic and clinical evaluation. Therefore, it is necessary to analyze Wilson’s variants in both the homozygous and the compound-heterozygous conditions to better understand the genotype-phenotype correlations and the incomplete penetrance observed in this disorder. Outlining clear phenotype-genotype associations is difficult due to a large number of mutations and different clinical presentations, but the involvement of epigenetic factors, modifying genes, environmental and lifestyle factors could explain the differences in evolution and onset in members of the same family and not only. Conclusions: Wilson’s disease is a genetically and clinically complex disorder. Although the results of genotype-phenotype correlation studies are not well defined, and in some cases are completely contradictory, some peculiarities related to the age of onset, sex, clinical phenotype, and the evolution of the disease have been highlighted. The interaction between genetic mutations and epigenetic factors may explain the phenotypic variability, but needs further study.

Low NUDT15 expression levels due to biallelic NUDT15 variants and 6-mercaptopurine intolerance.

6-Mercaptopurine (6-MP) is widely used for the treatment of paediatric leukaemia and lymphoma. Recently, germline variants in the NUDT15 gene have been identified as one of the major genetic causes for 6-MP-associated adverse effects such as myelosuppression. Patients with hypomorphic NUDT15 variants accumulate excessive levels of DNA-incorporated thioguanine in white blood cells, resulting in severe myelosuppression. Although preclinical studies suggest that these variants may influence the protein stability of NUDT15, this has not been directly characterised in patients. In this study, we report the development of a series of novel monoclonal antibodies against NUDT15, using which we quantitatively assessed NUDT15 protein levels in 37 patients with acute lymphoblastic leukaemia treated with 6-MP, using sandwich enzyme-linked immunosorbent assay (ELISA). The NUDT15 genotype was highly correlated with its protein levels (p< 0.0001), with homozygous and compound heterozygous patients showing exceedingly low NUDT15 expression. There was a positive correlation between NUDT15 protein level and 6-MP tolerance (r= 0.631, p< 0.0001). In conclusion, our results point to low NUDT15 protein abundance as the biochemical basis for NUDT15-mediated 6-MP intolerance, thus providing a phenotypic readout of inherited NUDT15 deficiency.

Clinical and Functional Study of a De Novo Variant in the PVP Motif of Kv1.1 Channel Associated with Epilepsy, Developmental Delay and Ataxia.

Mutations in the KCNA1 gene, encoding the voltage-gated potassium channel Kv1.1, have been associated with a spectrum of neurological phenotypes, including episodic ataxia type 1 and developmental and epileptic encephalopathy. We have recently identified a de novo variant in KCNA1 in the highly conserved Pro-Val-Pro motif within the pore of the Kv1.1 channel in a girl affected by early onset epilepsy, ataxia and developmental delay. Other mutations causing severe epilepsy are located in Kv1.1 pore domain. The patient was initially treated with a combination of antiepileptic drugs with limited benefit. Finally, seizures and ataxia control were achieved with lacosamide and acetazolamide. The aim of this study was to functionally characterize Kv1.1 mutant channel to provide a genotype–phenotype correlation and discuss therapeutic options for KCNA1-related epilepsy. To this aim, we transfected HEK 293 cells with Kv1.1 or P403A cDNAs and recorded potassium currents through whole-cell patch-clamp. P403A channels showed smaller potassium currents, voltage-dependent activation shifted by +30 mV towards positive potentials and slower kinetics of activation compared with Kv1.1 wild-type. Heteromeric Kv1.1+P403A channels, resembling the condition of the heterozygous patient, confirmed a loss-of-function biophysical phenotype. Overall, the functional characterization of P403A channels correlates with the clinical symptoms of the patient and supports the observation that mutations associated with severe epileptic phenotype cluster in a highly conserved stretch of residues in Kv1.1 pore domain. This study also strengthens the beneficial effect of acetazolamide and sodium channel blockers in KCNA1 channelopathies.

Genetic Biomarkers as Predictors of Response to Tocilizumab in Rheumatoid Arthritis: A Systematic Review and Meta-Analysis.

Rheumatoid arthritis (RA) is a lifelong, debilitating disease which incredibly impacts a patient’s quality of life if not treated to the optimal target. The clinical response of tocilizumab, an interleukin-6 (IL-6) inhibitor, is associated with several gene polymorphisms, particularly targeting the IL-6 pathway. This systematic review and meta-analysis seeks to investigate genetic biomarkers that predict the treatment outcome of tocilizumab therapy in RA patients. After evaluating the quality of retrieved records, five studies were chosen to carry out a quantitative synthesis involving 591 participants. We analysed genetic markers of IL-6R single nucleotide polymorphism (SNP)s rs12083537, rs2228145 and rs4329505, FCGR3A, CD69, GALNT18 and FCGR2A. A plausible finding based on meta-analysis revealed that RA patients with homozygous AA genotype for rs12083537 polymorphism of the IL-6R gene demonstrate a better response to TCZ treatment as opposed to homozygous and heterozygous patients with the G allele. Nonetheless, limitations in evaluating the available studies by meta-analysis include a lack of studies with dissimilarities in study design and outcome definitions, small sample sizes with low statistical power and heterogeneity of cohorts, a restricted the number of tested SNPs and small effects for the selected variants. Inconsistent finding remains as a great challenge to forge ahead towards personalised medicine for RA management.

^Sex Disparities in the Treatment and Outcomes of Familial Hypercholesterolemia

<h3>Lead Author's Financial Disclosures</h3> Nothing to disclose. <h3>Study Funding</h3> Fonds de recherche du Québec - Santé (FRQ-S). <h3>Background/Synopsis</h3> Familial hypercholesterolemia (FH), an inherited condition equally prevalent in males and females, is characterized by elevated low-density lipoprotein cholesterol (LDL-C) in the blood. If left untreated, FH leads to the development of premature atherosclerotic cardiovascular disease (ASCVD) and death. Many barriers to care in FH exist, which can result in low rates of diagnosis and suboptimal treatment and outcomes. Sex disparities have been identified as an important barrier to care in CVD, however their influence on treatment and lipid target achievement in FH remains to be explored. <h3>Objective/Purpose</h3> To determine sex differences in treatment and lipid level achievement in Heterozygous (HeFH) patients at the MUHC. <h3>Methods</h3> Here we performed a longitudinal registry analysis of sex differences in treatment and lipid level achievement in HeFH patients at the MUHC. Patients were included in the study if they were diagnosed as either "definite", "probable", or "possible" FH based on the Simon- Broome criteria, Dutch Lipid Clinic Network criteria, or the new Canadian FH definition. Differences between males and females were calculated using a t-test or chi-squared test. <h3>Results</h3> There were 127 females and 162 males from the McGill FH Registry included in the analysis. The mean age at the initial clinic visit was 49±17 years for females and 45±16 years for males (p=0.04). At the most recent clinic visit, there were more males (89%) than females (76%) taking statins (p=0.7), and only 35% of females were on high-intensity statins, compared to 74% of males (p=0.002). Interestingly, statin intolerance was reported in 40% of females and 22% of males (p=0.02). We then examined guideline-recommended lipid target achievement between both sexes. At baseline, males and females had similar mean LDL-C levels of 6.9±2.2 mmol/L and 6.7±1.6 mmol/L respectively (p=0.7). Despite this, at the most recent visit, 55% of males reached a target LDL-C of 2.5 mmol/L compared to just 32% of females (p=0.02). As well, from baseline to most recent visit, females reduced their LDL-C by 51%, whereas males lowered their LDL-C by 62% (p=0.01). Thus, fewer females are reaching appropriate guideline-based target LDL-C levels compared to males. <h3>Conclusions</h3> Our analysis reveals a sex bias in FH patients in favor of males regarding treatment intensity and lipid level target achievement. Identifying these imbalances will allow us to break down these barriers in care through educational initiatives and additional training, to improve quality of life and life expectancy of individuals with FH.

Identification of Novel and Known LDLR Variants Triggering Severe Familial Hypercholesterolemia in Saudi Families.

Familial hypercholesterolemia (FH) is a common illness mainly caused by variants occurring in the low-density lipoprotein receptor (LDLR) gene. FH is a leading cause of coronary artery disease. This study aims to determine genetic defect(s) in homozygous and heterozygous FH index patients and their first-degree blood relatives and understand the genotype-phenotype correlation. This study employed the genetic screening of FH-related genes by next-generation sequencing and cascade screening by capillary sequencing. We identified the presence of a novel frameshift variant [c.335_336insCGAG, p.(F114Rfs*17)] and three known missense variants [c.622G>A, p.(E208K)], [c.1474G>A, p.(D492N)], [c.1429G>A, p.(D477N)] in the LDLR gene of four unrelated Saudi families with FH. In proband 1, a nonsense variant c.1421C>G, p.(S474*) was also detected at exon 9 of the lipoprotein lipase gene. The segregation arrangement of the identified variants corresponded with the clinical characteristics. In this study, all the detected variants were confined in the ligand-binding domain and epidermal growth factor (EGF)-precursor homology domain of the LDLR protein, which portrayed severe clinical phenotypes of FH. Moreover, these LDLR variants were in a highly conserved residue of the proteins. In addition to the finding of the novel variant in the LDLR gene that extends the spectrum of variants causing FH, the results of this study also support the need for diagnostic screening and cascade genetic testing of this high-risk condition and to understand the genotype-phenotype correlation, which could lead to better prevention of coronary artery disease.

Abstract 5250: Association between UGT1A1 gene polymorphism and safety and efficacy of irinotecan monotherapy as the second-line treatment for advanced gastric cancer

Abstract Objective: Uridine diphosphate glucuronosyltransferase 1A1 (UGT1A1) is a key enzyme in irinotecan metabolism. However, the relationship between UGT1A1 genotype and the safety and efficacy of irinotecan monotherapy in the treatment of Chinese advanced gastric cancer remains unclear. Methods: A total of 110 patients were enrolled. Intravenous irinotecan was administered every 3 weeks. Irinotecan dose was selected according to the polymorphism of UGT1A1 gene, which was divided into 3 groups: UGT1A1*6 wild-type (GG type): 125mg/m2, d1, d8; UGT1A1*6 mutant heterozygosity (GA type) 100mg/m2, d1, d8; UGT1A1*6 homozygosity mutation (AA type) 75mg/m2, d1, d8 or paclitaxel 125mg/m2, d1, d8. UGT1A1 genotypes were determined by direct sequencing or next-generation sequencing of genomic DNA extracted from peripheral blood. Results: Among 110 patients of the subjects, the genotypes of UGT1A1*28 were wild-type in 78 patients (70.91%), mutant heterozygosity in 28 (25.45%) and mutant homozygosity in 4 (3.64%). UGT1A1*6 were GG in 67 cases (60.91%), GA in 35 cases (31.82%), and AA in 8 cases (7.27%). There were two heterozygous mutations in 3 patients, and no homozygous mutation was detected. A total of 10 cycles of irinotecan were administered, with a median of five cycles per patient. There was no significant difference in the risk of delayed diarrhea and granulocytopenia in patients with different UGT1A1*28 genotypes (P&amp;gt;0.05), while there was significant difference in the risk of delayed diarrhea and granulocytopenia in patients with different UGT1A1*6 genotypes (P&amp;lt;0.05). The dose intensity of irinotecan was different in patients with different subtypes of UGT1A1*6 gene, and the dose intensity of heterozygous mutant patients was lower than that of wild-type patients. However, there were no significant differences in PFS and OS among patients with different subtypes after dose adjustment and program adjustment (P&amp;gt;0.05). Conclusion: UGT1A1*6 gene polymorphism was significantly associated with diarrhea and neutropenia induced by irinotecan. The safety and effectiveness of antitumor therapy might be significantly improved by individualized drug administration according to the results of UGT1A1*6 gene polymorphism. Citation Format: Huifang Lv, Yunduan He, Caiyun Nie, Beibei Chen, Jianzheng Wang, Weifeng Xu, Jing Zhao, Xiaobing Chen, Junling Zhang. Association between UGT1A1 gene polymorphism and safety and efficacy of irinotecan monotherapy as the second-line treatment for advanced gastric cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5250.

Cirrhosis and Portal Hypertension in Compound Heterozygous People With Cystic Fibrosis Harboring One F508del CFTR Gene Mutation

Cirrhosis and Portal Hypertension in Compound Heterozygous People With Cystic Fibrosis Harboring One F508del CFTR Gene Mutation

Cognitive Impairment in a Complex Family With AAGGG and ACAGG Repeat Expansions in RFC1 Detected by ExpansionHunter Denovo.

We investigated the genetic basis and brain metabolism and blood flow of a Japanese family with spinocerebellar degeneration (SCD), with multiple affected members for 3 generations. After excluding DNA repeat expansion (RE) of common SCD genes by fragment analysis, we performed whole-exome sequencing (WES) and whole-genome sequencing (WGS). Homozygosity mapping was performed using these data. REs were investigated with WGS data using ExpansionHunter Denovo and Expansion Hunter. WES and WGS were unable to identify likely pathogenic variants, and homozygosity mapping failed to narrow down the locus. However, ExpansionHunter Denovo detected REs in intron 2 of the RFC1 gene and led us to the diagnosis of RFC1-related disorders. Subsequent repeat-primed PCR and Southern blot hybridization analyses revealed that 3 of 6 patients and 1 suspected individual had expansions of AAGGG ((AAGGG)exp) and (ACAGG)exp repeats in a compound heterozygous state and 3 had a homozygous (ACAGG)exp. The patients showed a variety of clinical features, including adult-onset ataxia, sensorimotor neuropathy, head tremor, parkinsonism, dystonia, and cognitive impairment. A comparison of previous reports with those of the family in study suggested that motor neuropathy could be a feature of compound heterozygous patients and biallelic (ACAGG)exp patients. Cognitive function tests showed cognitive impairment with a predominance of frontal lobe dysfunction. Examination of MRI, SPECT, and 18F-fluorodeoxyglucose-PET showed clear cortical damage with frontal lobe predominance in 1 case, but no cerebral damage was evident in the other 2 cases. Our report shows the usefulness of WGS and RE detection tools for SCD of unknown cause. The studied family with RFC1-related disorders included patients with (ACAGG)exp and (AAGGG)exp in a compound heterozygous state and was characterized by motor neuropathy. Based on the results of cognitive function tests and imaging studies, 1 patient presented with cognitive impairment due to frontal lobe metabolic changes, but there were also patients who presented with cognitive impairment without apparent cerebral metabolic or blood flow, suggesting that other factors are also associated with cognitive impairment.

Particular Evolutionary Aspects in Children with Cystic Fibrosis

Abstract Background: Cystic fibrosis was considered a fatal condition years ago but, nowadays, it can have a favorable evolution if diagnosed and treated early. Objective: Screening clinical aspects of patients suspected for cystic fibrosis and later diagnosed by means of specific sweat and genetic tests. Methods: A retrospective descriptive study was performed on 13 patients during five years, between 2015-2020 from the Pediatric Clinic of the Emergency County Hospital in Constanta. Results: There were five patients present in ΔF508 homozygous form, which it seems to be the most frequent mutation, translated by the deletion of phenylalanine at position 508. Among the heterozygous patients, 2 patients aged 10 and 14 years have the ΔF508 del 2.3 mutation; a 10-year-old patient has the mutation ΔF508, 2183 AA&gt;G; a 7-year-old patient has the ΔF508 R553X mutation; a 7-year-old patient has the N1303K, 394del TT mutation; a 1-year-old patient is heterozygous for the 394del TT and R347P mutations, a 3-year-old patient has the compound mutation ΔF508del and R334W, and finally, we find a 2-year-old patient heterozygous for the Δ508 mutation. Ten from 11 patients were diagnosed in the first year of life by performing the sweat test, and 2 patients based on the genetic test. In 30% of cases the onset manifestation were represented by diarrhea and growth failure, and 38% of cases had added respiratory manifestation. Singular manifestations such as respiratory disease, or respiratory disease accompanied by loss of appetite and growth failure, or chronic cough and steatorrhea followed by growth failure occurred in 8% each. If not properly diagnosed and treated, cystic fibrosis can put the patient’s life at risk. The analysis between an early diagnosis and the decrease of the incidence in pulmonary complications with pathogenic agents was statistically significant.

Treatment with IFB-088 Improves Neuropathy in CMT1A and CMT1B Mice

Charcot-Marie-Tooth disease type 1A (CMT1A), caused by duplication of the peripheral myelin protein 22 (PMP22) gene, and CMT1B, caused by mutations in myelin protein zero (MPZ) gene, are the two most common forms of demyelinating CMT (CMT1), and no treatments are available for either. Prior studies of the MpzSer63del mouse model of CMT1B have demonstrated that protein misfolding, endoplasmic reticulum (ER) retention and activation of the unfolded protein response (UPR) contributed to the neuropathy. Heterozygous patients with an arginine to cysteine mutation in MPZ (MPZR98C) develop a severe infantile form of CMT1B which is modelled by MpzR98C/ + mice that also show ER stress and an activated UPR. C3-PMP22 mice are considered to effectively model CMT1A. Altered proteostasis, ER stress and activation of the UPR have been demonstrated in mice carrying Pmp22 mutations. To determine whether enabling the ER stress/UPR and readjusting protein homeostasis would effectively treat these models of CMT1B and CMT1A, we administered Sephin1/IFB-088/icerguestat, a UPR modulator which showed efficacy in the MpzS63del model of CMT1B, to heterozygous MpzR98C and C3-PMP22 mice. Mice were analysed by behavioural, neurophysiological, morphological and biochemical measures. Both MpzR98C/ + and C3-PMP22 mice improved in motor function and neurophysiology. Myelination, as demonstrated by g-ratios and myelin thickness, improved in CMT1B and CMT1A mice and markers of UPR activation returned towards wild-type values. Taken together, our results demonstrate the capability of IFB-088 to treat a second mouse model of CMT1B and a mouse model of CMT1A, the most common form of CMT. Given the recent benefits of IFB-088 treatment in amyotrophic lateral sclerosis and multiple sclerosis animal models, these data demonstrate its potential in managing UPR and ER stress for multiple mutations in CMT1 as well as in other neurodegenerative diseases.Graphical (Left panel) the accumulation of overexpressed PMP22 or misfolded mutant P0 in the Schwann cell endoplasmic reticulum (ER) leads to overwhelming of the degradative capacity, activation of ER-stress mechanisms, and myelination impairment. (Right panel) by prolonging eIF2α phosphorylation, IFB-088 reduces the amount of newly synthesized proteins entering the ER, allowing the protein quality control systems to better cope with the unfolded/misfolded protein and allowing myelination to progress.