Analysis of TYR gene pathogenic variants in a Chinese Mongolian family with progressive symmetric erythrokeratoderma

Abstract Differentiating between inherited renal hypouricemia and transient hypouricemic status is challenging. Here, we aimed to describe the genetic background of hypouricemia patients using whole-exome sequencing (WES) and assess the feasibility for genetic diagnosis using two founder variants in primary screening. We selected all cases (N = 31) with extreme hypouricemia (<1.3 mg/dl) from a Korean urban cohort of 179,381 subjects without underlying conditions. WES and corresponding downstream analyses were performed for the discovery of rare causal variants for hypouricemia. Two known recessive variants within SLC22A12 (p.Trp258*, pArg90His) were identified in 24 out of 31 subjects (77.4%). In an independent cohort, we identified 50 individuals with hypouricemia and genotyped the p.Trp258* and p.Arg90His variants; 47 of the 50 (94%) hypouricemia cases were explained by only two mutations. Four novel coding variants in SLC22A12, p.Asn136Lys, p.Thr225Lys, p.Arg284Gln, and p.Glu429Lys, were additionally identified. In silico studies predict these as pathogenic variants. This is the first study to show the value of genetic diagnostic screening for hypouricemia in the clinical setting. Screening of just two ethnic-specific variants (p.Trp258* and p.Arg90His) identified 87.7% (71/81) of Korean patients with monogenic hypouricemia. Early genetic identification of constitutive hypouricemia may prevent acute kidney injury by avoidance of dehydration and excessive exercise.

Download Full-text

Lynch syndrome-related non-endometrioid endometrial cancer: analysis of outcomes

International Journal of Gynecological Cancer ◽

10.1136/ijgc-2019-000824 ◽

2019 ◽

Vol 30 (1) ◽

pp. 56-61

Author(s):

Giorgio Bogani ◽

Maria Grazia Tibiletti ◽

Maria Teresa Ricci ◽

Ileana Carnevali ◽

Viola Liberale ◽

...

Keyword(s):

Endometrial Cancer ◽

Lynch Syndrome ◽

Disease Free Survival ◽

Oncologic Outcomes ◽

Cox Models ◽

Matching Algorithm ◽

Pathogenic Variants ◽

Propensity Matching ◽

Endometrioid Endometrial Cancer

ObjectiveWomen with Lynch syndrome have a risk up to 40–60% of developing endometrial cancer, which is higher than their risk of developing colorectal or ovarian cancer. To date, no data on the outcomes of patients with Lynch syndrome diagnosed with non-endometrioid endometrial cancer are available. The goal of this study was to evaluate the outcome of patients with Lynch syndrome diagnosed with non-endometrioid endometrial cancer.MethodsData from consecutive patients diagnosed with Lynch syndrome and with a histological diagnosis of non-endometrioid endometrial cancer were retrospectively collected in two referral institutes in Italy. A case–control comparison (applying a propensity matching algorithm) was performed in order to compare patients with proven Lynch syndrome and controls. Inclusion criteria were: (a) histologically-proven endometrial cancer; (b) detection of a germline pathogenic variant in one of the MMR genes; (c) adequate follow-up. Only carriers of pathogenic or likely pathogenic variants (ie, class 5 and 4 according to the InSiGHT classification) were included in the study. Survival outcomes were assessed using KaplanMeier and Cox models.ResultsOverall, 137 patients with Lynch syndrome were collected. Mean patient age was 49.2 (10.9) years. Genes involved in the Lynch syndrome included MLH1, MSH2, and MSH6 in 43%, 39%, and 18% of cases, respectively. The study population included 27 patients with non-endometrioid endometrial cancer, who were matched 1:2 with patients with sporadic cancers using a propensity matching algorithm. After a median follow-up of 134 months (range 1–295), 2 (7.4%) of the 27 patients developed recurrent disease (3 and 36 months) and subsequently died of disease (7 and 91 months). Patients diagnosed with Lynch syndrome experienced better disease-free survival (HR 7.86 (95% CI 1.79 to 34.5); p=0.006) and overall survival (HR 5.33 (95% CI 1.18 to 23.9); p=0.029) than controls.ConclusionsNon-endometrioid endometrial cancer occurring in patients with Lynch syndrome might be associated with improved oncologic outcomes compared with controls. Genetic/molecular profiling should be investigated in order to better understand the mechanism underlying the prognosis.

Download Full-text

Use of SNP chips to detect rare pathogenic variants: retrospective, population based diagnostic evaluation

BMJ ◽

10.1136/bmj.n792 ◽

2021 ◽

pp. n792

Keyword(s):

Population Based ◽

Diagnostic Evaluation ◽

Pathogenic Variants

Download Full-text

Investigation of monogenic causes of familial breast cancer: data from the BEACCON case-control study

npj Breast Cancer ◽

10.1038/s41523-021-00279-9 ◽

2021 ◽

Vol 7 (1) ◽

Author(s):

Na Li ◽

Belle W. X. Lim ◽

Ella R. Thompson ◽

Simone McInerny ◽

Magnus Zethoven ◽

...

Keyword(s):

Breast Cancer ◽

High Risk ◽

Candidate Genes ◽

Familial Aggregation ◽

Loss Of Function ◽

Cancer Data ◽

Pathogenic Variants ◽

New Genes ◽

Predisposing Genes ◽

Predisposition Genes

AbstractBreast cancer (BC) has a significant heritable component but the genetic contribution remains unresolved in the majority of high-risk BC families. This study aims to investigate the monogenic causes underlying the familial aggregation of BC beyond BRCA1 and BRCA2, including the identification of new predisposing genes. A total of 11,511 non-BRCA familial BC cases and population-matched cancer-free female controls in the BEACCON study were investigated in two sequencing phases: 1303 candidate genes in up to 3892 cases and controls, followed by validation of 145 shortlisted genes in an additional 7619 subjects. The coding regions and exon–intron boundaries of all candidate genes and 14 previously proposed BC genes were sequenced using custom designed sequencing panels. Pedigree and pathology data were analysed to identify genotype-specific associations. The contribution of ATM, PALB2 and CHEK2 to BC predisposition was confirmed, but not RAD50 and NBN. An overall excess of loss-of-function (LoF) (OR 1.27, p = 9.05 × 10−9) and missense (OR 1.27, p = 3.96 × 10−73) variants was observed in the cases for the 145 candidate genes. Leading candidates harbored LoF variants with observed ORs of 2–4 and individually accounted for no more than 0.79% of the cases. New genes proposed by this study include NTHL1, WRN, PARP2, CTH and CDK9. The new candidate BC predisposition genes identified in BEACCON indicate that much of the remaining genetic causes of high-risk BC families are due to genes in which pathogenic variants are both very rare and convey only low to moderate risk.

Download Full-text

An epilepsy-causing mutation leads to co-translational misfolding of the Kv7.2 channel

BMC Biology ◽

10.1186/s12915-021-01040-1 ◽

2021 ◽

Vol 19 (1) ◽

Author(s):

Janire Urrutia ◽

Alejandra Aguado ◽

Carolina Gomis-Perez ◽

Arantza Muguruza-Montero ◽

Oscar R. Ballesteros ◽

...

Keyword(s):

Structural Instability ◽

Binding Assays ◽

Iq Motif ◽

Channel Function ◽

Human Epilepsy ◽

Pathogenic Variants ◽

In Silico Studies ◽

Nascent Chain

Abstract Background The amino acid sequence of proteins generally carries all the necessary information for acquisition of native conformations, but the vectorial nature of translation can additionally determine the folding outcome. Such consideration is particularly relevant in human diseases associated to inherited mutations leading to structural instability, aggregation, and degradation. Mutations in the KCNQ2 gene associated with human epilepsy have been suggested to cause misfolding of the encoded Kv7.2 channel. Although the effect on folding of mutations in some domains has been studied, little is known of the way pathogenic variants located in the calcium responsive domain (CRD) affect folding. Here, we explore how a Kv7.2 mutation (W344R) located in helix A of the CRD and associated with hereditary epilepsy interferes with channel function. Results We report that the epilepsy W344R mutation within the IQ motif of CRD decreases channel function, but contrary to other mutations at this site, it does not impair the interaction with Calmodulin (CaM) in vitro, as monitored by multiple in vitro binding assays. We find negligible impact of the mutation on the structure of the complex by molecular dynamic computations. In silico studies revealed two orientations of the side chain, which are differentially populated by WT and W344R variants. Binding to CaM is impaired when the mutated protein is produced in cellulo but not in vitro, suggesting that this mutation impedes proper folding during translation within the cell by forcing the nascent chain to follow a folding route that leads to a non-native configuration, and thereby generating non-functional ion channels that fail to traffic to proper neuronal compartments. Conclusions Our data suggest that the key pathogenic mechanism of Kv7.2 W344R mutation involves the failure to adopt a configuration that can be recognized by CaM in vivo but not in vitro.

Download Full-text

Whole-exome sequencing with targeted analysis and epilepsy after acute symptomatic neonatal seizures

Pediatric Research ◽

10.1038/s41390-021-01509-3 ◽

2021 ◽

Author(s):

Adam L. Numis ◽

Gilberto da Gente ◽

Elliott H. Sherr ◽

Hannah C. Glass

Keyword(s):

Exome Sequencing ◽

Whole Exome Sequencing ◽

De Novo ◽

List Type ◽

Sequencing Analysis ◽

Neonatal Seizures ◽

Pathogenic Variants ◽

Targeted Analysis ◽

Whole Exome ◽

Epilepsy Gene

Abstract Background The contribution of pathogenic gene variants with development of epilepsy after acute symptomatic neonatal seizures is not known. Methods Case–control study of 20 trios in children with a history of acute symptomatic neonatal seizures: 10 with and 10 without post-neonatal epilepsy. We performed whole-exome sequencing (WES) and identified pathogenic de novo, transmitted, and non-transmitted variants from established and candidate epilepsy association genes and correlated prevalence of these variants with epilepsy outcomes. We performed a sensitivity analysis with genes associated with coronary artery disease (CAD). We analyzed variants throughout the exome to evaluate for differential enrichment of functional properties using exploratory KEGG searches. Results Querying 200 established and candidate epilepsy genes, pathogenic variants were identified in 5 children with post-neonatal epilepsy yet in only 1 child without subsequent epilepsy. There was no difference in the number of trios with non-transmitted pathogenic variants in epilepsy or CAD genes. An exploratory KEGG analysis demonstrated a relative enrichment in cell death pathways in children without subsequent epilepsy. Conclusions In this pilot study, children with epilepsy after acute symptomatic neonatal seizures had a higher prevalence of coding variants with a targeted epilepsy gene sequencing analysis compared to those patients without subsequent epilepsy. Impact We performed whole-exome sequencing (WES) in 20 trios, including 10 children with epilepsy and 10 without epilepsy, both after acute symptomatic neonatal seizures. Children with post-neonatal epilepsy had a higher burden of pathogenic variants in epilepsy-associated genes compared to those without post-neonatal epilepsy. Future studies evaluating this association may lead to a better understanding of the risk of epilepsy after acute symptomatic neonatal seizures and elucidate molecular pathways that are dysregulated after brain injury and implicated in epileptogenesis.

Download Full-text