Distinguishing severe phenotypes associated with pathogenic variants in POLR3A.
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ABSTRACT:
SUBMITTER: Perrier S
PROVIDER: S-EPMC8758552 | biostudies-literature | 2022 Feb
REPOSITORIES: biostudies-literature
Publications
Distinguishing severe phenotypes associated with pathogenic variants in POLR3A.
Perrier Stefanie S Gauquelin Laurence L Wambach Jennifer A JA Bernard Geneviève G
American journal of medical genetics. Part A 20211112 2
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Project description:ImportanceCHEK2 pathogenic and likely pathogenic variants (PVs) are common, and low-risk (LR) variants, p.I157T, p.S428F, and p.T476M, are even more common. Biallelic CHEK2 PVs are associated with specific cancer phenotypes, including early age at onset of breast cancers. Whether biallelic LR variants are associated with cancer predisposition is unknown.ObjectiveTo characterize the cancer phenotype among individuals with biallelic CHEK2 variants, specifically those that have been associated with lower cancer risk in the heterozygous state.Design, setting, and participantsThis retrospective observational cohort study examining cancer phenotype by CHEK2 genotype was conducted at a single diagnostic genetic testing laboratory. Of 36 821 individuals who underwent genetic testing, 3783 (10.3%) with CHEK2 PVs or LR variants were ascertained from July 1, 2012, to September 30, 2019. Analyses were conducted from September 2022 to January 2024.ExposuresCancer phenotype among individuals with 2 LR variants and those with 1 PV and 1 LR variant was compared with cancer phenotype among individuals with wild type (WT) (n = 33 034), single LR variant (n = 1566), single PV controls (n = 2167), and 2 PVs (n = 21). Cancer phenotypes were investigated for any cancer, multiple primary cancers, female breast cancer, and bilateral female breast cancers.Main outcomes and measuresCancer phenotype of CHEK2 2 LRs and 1 PV and 1 LR.ResultsOf 36 821 individuals, 92.1% were female, and the median age at testing was 53 years (IQR, 44-63 years); 3787 (10.3%) were identified as having a CHEK2 PV or LR variant. There were 13 individuals with 2 LR variants and 20 with 1 PV and 1 LR variant. Among those with 2 LR variants, prevalence of any cancer (76.9%) and breast cancer (60.0%) were similar to those with WT (any cancer, 69.8%; breast cancer, 52.7%) and those with a single LR variant (any cancer, 70.9%; breast cancer, 57.5%). Among participants with 1 PV and 1 LR variant, 95.0% had a prior cancer diagnosis, a higher rate than among those with a single PV (76.8%), but the difference was not statistically significant. Among female individuals with 1 PV and 1 LR variant, 86.7% had a breast cancer diagnosis, compared with 67.1% with a single PV, although these differences were not statistically significant.Conclusions and relevanceIn this cohort study, individuals with 2 LR variants in CHEK2 had a cancer phenotype similar to those with a single LR variant and similar to WT controls. Individuals with 1 PV and 1 LR variant may have a more penetrant cancer phenotype than individuals with a single PV. Future studies focused on CHEK2 LR variants will aid in better understanding whether these variants are genetic modifiers associated with cancer risk.
| S-EPMC11696452 | biostudies-literature
Project description:PurposeSeveral clinical phenotypes including fetal hydrops, central conducting lymphatic anomaly or capillary malformations with arteriovenous malformations 2 (CM-AVM2) have been associated with EPHB4 (Ephrin type B receptor 4) variants, demanding new approaches for deciphering pathogenesis of novel variants of uncertain significance (VUS) identified in EPHB4, and for the identification of differentiated disease mechanisms at the molecular level.MethodsTen index cases with various phenotypes, either fetal hydrops, CM-AVM2, or peripheral lower limb lymphedema, whose distinct clinical phenotypes are described in detail in this study, presented with a variant in EPHB4. In vitro functional studies were performed to confirm pathogenicity.ResultsPathogenicity was demonstrated for six of the seven novel EPHB4 VUS investigated. A heterogeneity of molecular disease mechanisms was identified, from loss of protein production or aberrant subcellular localization to total reduction of the phosphorylation capability of the receptor. There was some phenotype-genotype correlation; however, previously unreported intrafamilial overlapping phenotypes such as lymphatic-related fetal hydrops (LRFH) and CM-AVM2 in the same family were observed.ConclusionThis study highlights the usefulness of protein expression and subcellular localization studies to predict EPHB4 variant pathogenesis. Our accurate clinical phenotyping expands our interpretation of the Janus-faced spectrum of EPHB4-related disorders, introducing the discovery of cases with overlapping phenotypes.
| S-EPMC8257501 | biostudies-literature
Project description:Genetic testing for long-QT syndrome (LQTS) has diagnostic, prognostic, and therapeutic implications. Hundreds of causative mutations in 12 known LQTS-susceptibility genes have been identified. Genetic testing that includes the 3 most commonly mutated genes is available clinically. Distinguishing pathogenic mutations from innocuous rare variants is critical to the interpretation of test results. We sought to quantify the value of mutation type and gene/protein region in determining the probability of pathogenicity for mutations.Type, frequency, and location of mutations across KCNQ1 (LQT1), KCNH2 (LQT2), and SCN5A (LQT3) were compared between 388 unrelated "definite" (clinical diagnostic score >or=4 and/or QTc >or=480 ms) cases of LQTS and >1300 healthy controls for each gene. From these data, estimated predictive values (percent of mutations found in definite cases that would cause LQTS) were determined according to mutation type and location. Mutations were 10 times more common in cases than controls (0.58 per case versus 0.06 per control). Missense mutations were the most common, accounting for 78%, 67%, and 89% of mutations in KCNQ1, KCNH2, and SCN5A in cases and >95% in controls. Nonmissense mutations have an estimated predictive value >99% regardless of location. In contrast, location appears to be critical for characterizing missense mutations. Relative frequency of missense mutations between cases and controls ranged from approximately 1:1 in the SCN5A interdomain linker to infinity in the pore, transmembrane, and linker in KCNH2. These correspond to estimated predictive values ranging from 0% in the interdomain linker of SCN5A to 100% in the transmembrane/linker/pore regions of KCNH2. The estimated predictive value is also high in the linker, pore, transmembrane, and C terminus of KCNQ1 and the transmembrane/linker of SCN5A.Distinguishing pathogenic mutations from rare variants is of critical importance in the interpretation of genetic testing in LQTS. Mutation type, mutation location, and ethnic-specificshould be viewed as variants of uncertain significance and prompt further investigation to clarify the likelihood of disease causation. However, mutations in regions such as the transmembrane, linker, and pore of KCNQ1 and KCNH2 may be defined confidently as high-probability LQTS-causing mutations. These findings will have implications for other genetic disorders involving mutational analysis.
| S-EPMC3025752 | biostudies-literature
Project description:PurposeOur understanding of inborn errors of immunity is increasing; however, their contribution to pediatric sepsis is unknown.MethodsWe used whole-exome sequencing (WES) to characterize variants in genes related to monogenic immunologic disorders in 330 children admitted to intensive care for severe sepsis. We defined candidate variants as rare variants classified as pathogenic or potentially pathogenic in QIAGEN's Human Gene Mutation Database or novel null variants in a disease-consistent inheritance pattern. We investigated variant correlation with infection and inflammatory phenotype.ResultsMore than one in two children overall and three of four African American children had immunodeficiency-associated variants. Children with variants had increased odds of isolating a blood or urinary pathogen (blood: OR 2.82, 95% CI: 1.12-7.10, p = 0.023, urine: OR: 8.23, 95% CI: 1.06-64.11, p = 0.016) and demonstrating increased inflammation with hyperferritinemia (ferritin [Formula: see text] ng/mL, OR: 2.16, 95% CI: 1.28-3.66, p = 0.004), lymphopenia (lymphocyte count < 1000/µL, OR: 1.66, 95% CI: 1.06 - 2.60, p = 0.027), thrombocytopenia (platelet count < 150,000/µL, OR: 1.76, 95% CI: 1.12-2.76, p = 0.013), and CRP greater than 10 mg/dl (OR: 1.71, 95% CI: 1.10-2.68, p = 0.017). They also had increased odds of requiring extracorporeal membrane oxygenation (ECMO, OR: 4.19, 95% CI: 1.21-14.5, p = 0.019).ConclusionHerein, we describe the genetic findings in this severe pediatric sepsis cohort and their microbiologic and immunologic significance, providing evidence for the phenotypic effect of these variants and rationale for screening children with life-threatening infections for potential inborn errors of immunity.
| S-EPMC8720168 | biostudies-literature
Project description:ObjectivesThis study aimed to investigate the clinical, radiological, and genetic features of POLR3-related leukodystrophy caused by mutations in POLR3A or POLR1C.MethodsFourteen Chinese patients with POLR3-related leukodystrophy were enrolled in this cross-sectional observational study. The clinical manifestations, brain MRI and genetic tests of the patients were evaluated.ResultsThirteen patients had biallelic variants in POLR3A (92.9%), and one had biallelic variants in POLR1C (7.1%). The median age at disease onset was 9 months. A total of 85.7% of the patients presented with motor delay, abnormal gait, and intelligence disability in the first 2 years of life. Intellectual disability can be categorized based on its severity. It varied from mild (which involves difficulty concentrating) to very severe (with no smiling or laughing or never being able to speak since birth). Short stature was observed in all patients, and delayed dentition was observed in 64.3% of them. Furthermore, three out of 14 patients had myopia. Hypomyelination was invariably present in all patients, whereas myelination of the basal ganglia was preserved in only six out of 14 patients. All the mutations were compound heterozygous and included missense (n = 25), deletion (n = 1), and splice site variants (n = 2). A total of 78.6% of the patients with POLR3A were identified as carrying the c.1771-6C>G variant or the c.1771-7C>G variant.ConclusionThe phenotypic diversity of POLR3-HLD associated with pathogenic variants ranges from mild to very severe for neurological and non-neurological symptoms. Most patients presented symptoms in the first 2 years of life. The c.1771-6C>G or c.1771-7C>G variant is the most frequent mutation site in POLR3A in Chinese individuals.
| S-EPMC10972892 | biostudies-literature
Project description: Not available
| S-EPMC5837469 | biostudies-literature
Project description:Biallelic variants in POLR3A cause 4H leukodystrophy, characterized by hypomyelination in combination with cerebellar and pyramidal signs and variable non-neurological manifestations. Basal ganglia are spared in 4H leukodystrophy, and dystonia is not prominent. Three patients with variants in POLR3A, an atypical presentation with dystonia, and MR involvement of putamen and caudate nucleus (striatum) and red nucleus have previously been reported. Genetic, clinical findings and 18 MRI scans from nine patients with homozygous or compound heterozygous POLR3A variants and predominant striatal changes were retrospectively reviewed in order to characterize the striatal variant of POLR3A-associated disease. Prominent extrapyramidal involvement was the predominant clinical sign in all patients. The three youngest children were severely affected with muscle hypotonia, impaired head control, and choreic movements. Presentation of the six older patients was milder. Two brothers diagnosed with juvenile parkinsonism were homozygous for the c.1771-6C > G variant in POLR3A; the other seven either carried c.1771-6C > G (n = 1) or c.1771-7C > G (n = 7) together with another variant (missense, synonymous, or intronic). Striatal T2-hyperintensity and atrophy together with involvement of the superior cerebellar peduncles were characteristic. Additional MRI findings were involvement of dentate nuclei, hila, or peridentate white matter (3, 6, and 4/9), inferior cerebellar peduncles (6/9), red nuclei (2/9), and abnormal myelination of pyramidal and visual tracts (6/9) but no frank hypomyelination. Clinical and MRI findings in patients with a striatal variant of POLR3A-related disease are distinct from 4H leukodystrophy and associated with one of two intronic variants, c.1771-6C > G or c.1771-7C > G, in combination with another POLR3A variant.
| S-EPMC7064625 | biostudies-literature
Project description: Not available
| S-EPMC5837678 | biostudies-literature
Project description:De novo pathogenic variants in CHAMP1 (chromosome alignment maintaining phosphoprotein 1), which encodes kinetochore-microtubule associated protein on 13q34, cause a rare neurodevelopmental disorder. We enrolled 14 individuals with pathogenic variants in CHAMP1 that were documented by exome sequencing or gene panel sequencing. Medical history interviews, seizure surveys, Vineland Adapted Behavior Scales Second Edition, and other behavioral surveys were completed by primary caregivers of available participants in Simons Searchlight. Clinicians extracted clinical data from the medical record for two participants. We report on clinical features of 14 individuals (ages 2-26) with de novo predicted loss-of-function variants in CHAMP1 and compare them with previously reported cases (total n = 32). At least two individuals have the same de novo variant: p.(Ser181Cysfs*5), p.(Trp348*), p.(Arg398*), p.(Arg497*), or p.(Tyr709*). Common phenotypes include intellectual disability/developmental delay, language impairment, congenital and acquired microcephaly, behavioral problems including autism spectrum disorder, seizures, hypotonia, gastrointestinal issues of reflux and constipation, and ophthalmologic issues. Other rarely observed phenotypes include leukemia, failure to thrive, and high pain tolerance. Pathogenic variants in CHAMP1 are associated with a variable clinical phenotype of developmental delay/intellectual disability and seizures.
| S-EPMC8327885 | biostudies-literature
Project description:ObjectiveThis study describes 5 novel variants of 7 KMT2D/KDM6A gene and summarizes the clinical manifestations and the mutational spectrum of 47 Chinese Kabuki syndrome (KS) patients.MethodsBlood samples were collected for whole-exome sequencing (WES) for 7 patients and their parents if available. Phenotypic and genotypic spectra of 40 previously published unrelated Chinese KS patients were summarized.ResultGenetic sequencing identified six KMT2D variants (c.3926delC, c.5845delC, c.6595delT, c.12630delG, c.16294C > T, and c.16442delG) and one KDM6A variant (c.2668-2671del). Of them, 4 variants (c.3926delC, c.5845delC, c.12630delG, and c.16442delG) in KMT2D gene and the variant (c.2668-2671del) in KDM6A gene were novel. Combining with previously published Chinese KS cases, the patients presented with five cardinal manifestations including facial dysmorphism, intellectual disability, growth retardation, fingertip pads and skeletal abnormalities. In addition, 29.5% (5/17) patients had brain abnormalities, such as hydrocephalus, cerebellar vermis dysplasia, thin pituitary and white matter myelination delay, corpus callosum hypoplasia and Dandy-Walker malformation.ConclusionIn this report, five novel variants in KMT2D/KDM6A genes are described. A subset of Chinese KS patients presented with brain abnormalities that were not previously reported. Our study expands the mutational and phenotypic spectra of KS.
| S-EPMC6854618 | biostudies-literature