Shared germline genomic variants in two patients with double primary gastrointestinal stromal tumours (GISTs).

BACKGROUND: Gastrointestinal stromal tumours (GISTs) are prevalent mesenchymal tumours of the gastrointestinal tract, commonly exhibiting structural variations in KIT and PDGFRA genes. While the mutational profiling of somatic tumours is well described, the genes behind the susceptibility to develop GIST are not yet fully discovered. This study explores the genomic landscape of two primary GIST cases, aiming to identify shared germline pathogenic variants and shed light on potential key players in tumourigenesis. METHODS: Two patients with distinct genotypically and phenotypically GISTs underwent germline whole genome sequencing. CNV and single nucleotide variant (SNV) analyses were performed. RESULTS: Both patients harbouring low-risk GISTs with different mutations (PDGFRA and KIT) shared homozygous germline pathogenic deletions in both CFHR1 and CFHR3 genes. CNV analysis revealed additional shared pathogenic deletions in other genes such as SLC25A24. No particular pathogenic SNV shared by both patients was detected. CONCLUSION: Our study provides new insights into germline variants that can be associated with the development of GISTs, namely, CFHR1 and CFHR3 deep deletions. Further functional validation is warranted to elucidate the precise contributions of identified germline mutations in GIST development.

Estimating cancer risk in carriers of Lynch syndrome variants in UK Biobank.

BackgroundLynch syndrome (LS) is an inherited cancer predisposition syndrome caused by genetic variants affecting DNA mismatch repair (MMR) genes MLH1, MSH2, MSH6 and PMS2 Cancer risk in LS is estimated from cohorts of individuals ascertained by individual or family history of cancer, which may upwardly bias estimates. METHODS: 830 carriers of pathogenic or likely pathogenic (path_MMR) MMR gene variants classified by InSiGHT were identified in 454 756 UK Biobank (UKB) participants using whole-exome sequence. Nelson-Aalen survival analysis was used to estimate cumulative incidence of colorectal, endometrial and breast cancer (BC). RESULTS: Cumulative incidence of colorectal and endometrial cancer (EC) by age 70 years was elevated in path_MMR carriers compared with non-carriers (colorectal: 11.8% (95% confidence interval (CI): 9.5% to 14.6%) vs 1.7% (95% CI: 1.6% to 1.7%), endometrial: 13.4% (95% CI: 10.2% to 17.6%) vs 1.0% (95% CI: 0.9% to 1.0%)), but the magnitude of this increase differed between genes. Cumulative BC incidence by age 70 years was not elevated in path_MMR carriers compared with non-carriers (8.9% (95% CI: 6.3% to 12.4%) vs 7.5% (95% CI: 7.4% to 7.6%)). Cumulative cancer incidence estimates in UKB were similar to estimates from the Prospective Lynch Syndrome Database for all genes and cancers, except there was no evidence for elevated EC risk in carriers of pathogenic PMS2 variants in UKB. CONCLUSION: These results support offering incidentally identified carriers of any path_MMR surveillance to manage colorectal cancer risk. Incidentally identified carriers of pathogenic variants in MLH1, MSH2 and MSH6 would also benefit from interventions to reduce EC risk. The results suggest that BC is not an LS-related cancer.

Variant classification changes over time in the clinical molecular diagnostic laboratory setting.

BACKGROUND: Variant classification in the setting of germline genetic testing is necessary for patients and their families to receive proper care. Variants are classified as pathogenic (P), likely pathogenic (LP), uncertain significance (VUS), likely benign (LB) and benign (B) using the standards and guidelines recommended by the American College of Medical Genetics and the Association for Molecular Pathology, with modifications for specific genes. As the literature continues to rapidly expand, and evidence continues to accumulate, prior classifications can be updated accordingly. In this study, we aim to characterise variant reclassifications in Ontario. METHODS: DNA samples from patients seen at hereditary cancer clinics in Ontario from January 2012 to April 2022 were submitted for testing. Patients met provincial eligibility criteria for testing for hereditary cancer syndromes or polycystic kidney disease. Reclassification events were determined to be within their broader category of significance (B to LB or vice versa, or P to LP or vice versa) or outside of their broader category as significance (ie, significant reclassifications from B/LB or VUS or P/LP, from P/LP to VUS or B/LB, or from VUS to any other category). RESULTS: Of the 8075 unique variants included in this study, 23.7% (1912) of variants were reassessed, and 7.2% (578) of variants were reclassified. Of these, 351 (60.7%) variants were reclassified outside of their broader category of significance. Overall, the final classification was significantly different for 336 (58.1%) variants. Importantly, most reclassified variants were downgraded to a more benign classification (n=245; 72.9%). Of note, most reclassified VUS was downgraded to B/LB (n=233; 84.7%). CONCLUSIONS: The likelihood for reclassification of variants on reassessment is high. Most reclassified variants were downgraded to a more benign classification. Our findings highlight the importance of periodic variant reassessment to ensure timely and appropriate care for patients and their families.

Novel truncating germline variant reinforces TINF2 as a susceptibility gene for familial non-medullary thyroid cancer.

BACKGROUND: It has long been observed that there are families in which non-medullary thyroid cancer (NMTC) occurs, but few syndromes and genes have been described to date. Proteins in the shelterin complex have been implied in cancer. Here, we have studied shelterin genes in families affected by NMTC (FNMTC). METHODS: We performed whole-exome sequencing (WES) in 10 affected individuals from four families with at least three affected members. Polymerase chain reaction (PCR) and Sanger sequencing were performed to search for variants in the TINF2 gene in 40 FNMTC families. TINF2 transcripts and loss of heterozygosity (LOH) were studied in several affected patients of one family. RESULTS: We found the c.507G>T variant in heterozygosis in the TINF2 gene in one family, co-segregating in all five affected members. This variant affects the normal splicing. LOH was not observed. CONCLUSIONS: Our results reinforce the TINF2 gene as a susceptibility cause of FNMTC suggesting the importance of location of frameshift variants in TINF2. According to our data and previous literature, TINF2 pathogenic variants appear to be a significant risk factor for the development of NMTC and/or melanoma.

Differential rates of germline heterozygote and mosaic variants in NF2 may show varying propensity for meiotic or mitotic mutation.

NF2-related schwannomatosis is an autosomal dominant tumour predisposition condition that causes multiple benign tumours of the nervous system, especially schwannomas. This results from germline pathogenic variants in the NF2 gene, which are most commonly de novo NF2 nonsense variants. Over half of these de novo variants occur at just six CpG dinucleotides. In this study, we show that the six NF2 CpG nonsense variants make up 54% (136/252) of de novo nonsense variants, despite constituting <10% of nonsense positions in the germline (total=62), and that this pattern is different from the APC gene, which is also known to have a high rate of mosaicism. In addition, the NF2 c.586C>T; p.(Arg196Ter) has a higher de novo heterozygote to mosaicism ratio than the five other CpG variants (73.1% vs 53.7%, p=0.03) and the neighbouring CpG variant (NF2 c.592C>T; p.(Arg198Ter) 38.5%, p=0.02). This may be due to differences in rates of mutation at meiosis versus mitosis.

High yield of surveillance in patients diagnosed with constitutional mismatch repair deficiency.

BACKGROUND: Constitutional mismatch repair deficiency (CMMRD) is a rare autosomal recessively inherited syndrome that is caused by biallelic pathogenic variants of the mismatch repair genes. It is characterised by the development of multiple tumours in the first and second decade of life including brain, gastrointestinal and haematological tumours often resulting in early death. In order to improve the prognosis of these patients, the European collaborative group 'care for CMMRD' developed a surveillance programme in 2014 and established a registry of patients with CMMRD in Paris. The aim of the study was to evaluate the outcome of this programme. METHODS: Twenty-two patients with a definitive diagnosis of CMMRD and with at least one follow-up study were selected from the registry. Medical data on the outcome of surveillance were collected from these patients. RESULTS: During a mean follow-up of 4 years, the programme detected eight malignant tumours including three brain tumours, three upper gastrointestinal cancers and two colorectal cancers. Most tumours could successfully be treated. In addition, many adenomas were detected in the duodenum, and colorectum and subsequently removed. Seven patients developed a symptomatic malignancy, including two brain tumours, one small bowel cancer and four haematological malignancies. At the end of the follow-up, 16 out of 22 patients (73%) who participated in the surveillance programme were still alive. CONCLUSION: The study suggests a beneficial effect of surveillance of the digestive tract and brains.

Profiling of the genetic features of Chinese patients with gastric cancer with HRD germline mutations in a large-scale retrospective study.

BACKGROUND: Approximately 10% of gastric cancers (GCs) are associated with strong familial clustering and can be attributed to genetic predisposition. Homologous recombination deficiency (HRD) leads to genomic instability and accumulation of genetic variations, playing an important role in the development and progression of cancer. We aimed to delineate the germline mutation characteristics of patients with HRD-mut GC in Chinese. METHODS: We retrospectively reviewed the genomic sequencing data of 1135 patients with Chinese GC. Patients harbouring at least one loss of function (LoF) germline mutations in BRCA1, BRCA2, ATM, PALB2, BRIP1, CHEK1, CHEK2, FANCA and FANCL were selected for analysis. RESULTS: 89 patients were identified with LoF germline mutations of HRD gene. Germline mutations occurred most commonly in ATM (30.33%), followed by BRIP1 (17.98%), BRCA2 (14.61%), BRCA1 (12.36%), FANCA (10.11%), PALB2 (10.11%), FANCL (6.74%), CHEK1 (3.37%) and CHEK2 (3.37%). 14 out of 89 patients with HRD-mut harboured double mutations in HRD and MMR genes, with the median age of 51.5 years. The decreasing median age would be attributed to five patients with HRD+MMR double-muts harbouring mutations in both HRD and MMR genes. The median age of onset of patients with HRD+MMR double-muts is 47, which is significantly earlier than that of Chinese patients with GC (p=0.0235). CONCLUSION: Our data suggest that carrying both HRD and MMR gene LoF germline mutations may cause early-onset GC. Germline mutations in the HRD gene should be of concern in the study of hereditary GC.

Congenital mirror movements are associated with defective polymerisation of RAD51.

BACKGROUND: Mirror movements are involuntary movements of one hand that mirror intentional movements of the other hand. Congenital mirror movements (CMM) is a rare genetic disorder with autosomal dominant inheritance, in which mirror movements are the main neurological manifestation. CMM is associated with an abnormal decussation of the corticospinal tract, a major motor tract for voluntary movements. RAD51 is known to play a key role in homologous recombination with a critical function in DNA repair. While RAD51 haploinsufficiency was first proposed to explain CMM, other mechanisms could be involved. METHODS: We performed Sanger sequencing of RAD51 in five newly identified CMM families to identify new pathogenic variants. We further investigated the expression of wild-type and mutant RAD51 in the patients' lymphoblasts at mRNA and protein levels. We then characterised the functions of RAD51 altered by non-truncating variants using biochemical approaches. RESULTS: The level of wild-type RAD51 protein was lower in the cells of all patients with CMM compared with their non-carrier relatives. The reduction was less pronounced in asymptomatic carriers. In vitro, mutant RAD51 proteins showed loss-of-function for polymerisation, DNA binding and strand exchange activity. CONCLUSION: Our study demonstrates that RAD51 haploinsufficiency, including loss-of-function of non-truncating variants, results in CMM. The incomplete penetrance likely results from post-transcriptional compensation. Changes in RAD51 levels and/or polymerisation properties could influence guidance of the corticospinal axons during development. Our findings open up new perspectives to understand the role of RAD51 in neurodevelopment.

Contribution of large genomic rearrangements in PALB2 to familial breast cancer: implications for genetic testing.

BACKGROUND: PALB2 is the most important contributor to familial breast cancer after BRCA1 and BRCA2. Large genomic rearrangements (LGRs) in BRCA1 and BRCA2 are routinely assessed in clinical testing and are a significant contributor to the yield of actionable findings. In contrast, the contribution of LGRs in PALB2 has not been systematically studied. METHODS: We performed targeted sequencing and real-time qPCR validation to identify LGRs in PALB2 in 5770 unrelated patients with familial breast cancer and 5741 cancer-free control women from the same Australian population. RESULTS: Seven large deletions ranging in size from 0.96 kbp to 18.07 kbp involving PALB2 were identified in seven cases, while no LGRs were identified in any of the controls. Six LGRs were considered pathogenic as they included one or more exons of PALB2 and disrupted the WD40 domain at the C terminal end of the PALB2 protein while one LGR only involved a partial region of intron 10 and was considered a variant of unknown significance. Altogether, pathogenic LGRs identified in this study accounted for 10.3% (6 of 58) of the pathogenic PALB2 variants detected among the 5770 families with familial breast cancer. CONCLUSIONS: Our data show that a clinically important proportion of PALB2 pathogenic mutations in Australian patients with familial breast cancer are LGRs. Such observations have provided strong support for inclusion of PALB2 LGRs in routine clinical genetic testing.

MRM2 variants in families with complex dystonic syndromes: evidence for phenotypic heterogeneity.

BACKGROUND: Dystonia involves repetitive movements and muscle contractions leading to abnormal postures. We investigated patients in two families, DYAF11 and M, exhibiting dystonic or involuntary movement disorders. METHODS: Clinical investigations were performed for all patients. Genetic analyses included genome-wide linkage analysis and exome sequencing followed by Sanger sequencing validation. MRM2-specific transcripts were analysed from participants' blood samples in Family DYAF11 after cloning of gene-specific cDNA. RESULTS: Four affected siblings in Family DYAF11 had progressive dystonic features. Two patients in Family M exhibited a neurodevelopmental disorder accompanied by involuntary movements. In Family DYAF11, linkage was detected to the telomere at chromosome 7p22.3, spanning <2 Mb. Exome sequencing identified a donor splice-site variant, c.8+1G>T in MRM2, which segregated with the phenotype, corresponding to the linkage data since all affected individuals were homozygous while the obligate unaffected carriers were heterozygous for the variant. In the MRM2 c.8+1G>T allele, an aberrant alternative acceptor splice-site located within exon 2 was used in a subset of the transcripts, creating a frameshift in the open reading frame. Exome sequencing in Family M revealed a rare missense variant c.242C>T, p.(Ala81Val), which affected a conserved amino acid. CONCLUSIONS: Our results expand the clinical and allelic spectrum of MRM2 variants. Previously, these descriptions were based on observations in a single patient, diagnosed with mitochondrial DNA depletion syndrome 17, in whom movement disorder was accompanied by recurrent strokes and epilepsy. We also demonstrate a subset of correctly spliced tt-ag MRM2 transcripts, raising the possibility to develop treatment by understanding the disease mechanism.

Germline pathogenic SMARCA4 variants in neuroblastoma.

Heterozygous germline pathogenic variants (GPVs) in SMARCA4, the gene encoding the ATP-dependent chromatin remodelling protein SMARCA4 (previously known as BRG1), predispose to several rare tumour types, including small cell carcinoma of the ovary, hypercalcaemic type, atypical teratoid and malignant rhabdoid tumour, and uterine sarcoma. The increase in germline testing of SMARCA4 in recent years has revealed putative GPVs affecting SMARCA4 in patients with other cancer types. Here we describe 11 patients with neuroblastoma (NBL), including 4 previously unreported cases, all of whom were found to harbour heterozygous germline variants in SMARCA4 Median age at diagnosis was 5 years (range 2 months-26 years); nine were male; and eight of nine cases had tumour location information in the adrenal gland. Eight of the germline variants were expected to result in loss of function of SMARCA4 (large deletion, truncating and canonical splice variants), while the remaining four were missense variants. Loss of heterozygosity of the wild-type SMARCA4 allele was found in all eight cases where somatic testing was performed, supporting the notion that SMARCA4 functions as a classic tumour suppressor. Altogether, these findings strongly suggest that NBL should be included in the spectrum of SMARCA4-associated tumours.

Polymorphic variants involved in methylation regulation: a strategy to discover risk loci for pancreatic ductal adenocarcinoma.

INTRODUCTION: Only a small number of risk factors for pancreatic ductal adenocarcinoma (PDAC) has been established. Several studies identified a role of epigenetics and of deregulation of DNA methylation. DNA methylation is variable across a lifetime and in different tissues; nevertheless, its levels can be regulated by genetic variants like methylation quantitative trait loci (mQTLs), which can be used as a surrogate. MATERIALS AND METHODS: We scanned the whole genome for mQTLs and performed an association study in 14 705 PDAC cases and 246 921 controls. The methylation data were obtained from whole blood and pancreatic cancer tissue through online databases. We used the Pancreatic Cancer Cohort Consortium and the Pancreatic Cancer Case-Control Consortium genome-wide association study (GWAS) data as discovery phase and the Pancreatic Disease Research consortium, the FinnGen project and the Japan Pancreatic Cancer Research consortium GWAS as replication phase. RESULTS: The C allele of 15q26.1-rs12905855 showed an association with a decreased risk of PDAC (OR=0.90, 95% CI 0.87 to 0.94, p=4.93×10-8 in the overall meta-analysis), reaching genome-level statistical significance. 15q26.1-rs12905855 decreases the methylation of a 'C-phosphate-G' (CpG) site located in the promoter region of the RCCD1 antisense (RCCD1-AS1) gene which, when expressed, decreases the expression of the RCC1 domain-containing (RCCD1) gene (part of a histone demethylase complex). Thus, it is possible that the rs12905855 C-allele has a protective role in PDAC development through an increase of RCCD1 gene expression, made possible by the inactivity of RCCD1-AS1. CONCLUSION: We identified a novel PDAC risk locus which modulates cancer risk by controlling gene expression through DNA methylation.

Surgical phenotype of patients with peritoneal mesothelioma and a germline mutation.

BACKGROUND: This study aimed to investigate if peritoneal mesothelioma (PM) patients with germline mutations (GM) have distinct surgical characteristics when compared to those without GM. METHODS: PM patients were selected from an ongoing prospective study that conducts germline testing of 82 susceptibility genes. Germline status was correlated with surgical data obtained from a prospectively collected database using univariate, multivariate, and receiver operating characteristic (ROC) analyses. RESULTS: Out of 88 PM patients enrolled between 2009 and 2019, 18 GMs (20.5%) were identified in BRCA1-associated protein 1 (BAP1) (n = 11, 12.5% of all patients), SDHA (n = 2) and WT1, CDKN2A, CHEK2, ATM, and BRCA2 (n = 1 patient each). Surgical procedures were performed in 71 patients, the most common of which were cytoreductive surgeries with hyperthermic intraperitoneal chemotherapy (n = 61). Patients with GM presented with a higher prevalence of other prior cancers (61.1% vs. 31.4%, p = .02) and lower platelet count (251 [160-413] vs. 367 [196-780] K/µL, p = .005) compared to those without GM (n = 70). Survival outcomes did not differ significantly between the groups. Patients with BAP1 GMs were more likely to develop bicavitary disease and to present with lower platelet count and mitotic count score, and higher peritoneal cancer index (PCI, all p ≤ .04) compared with those without GM. On ROC analysis, the combination of PCI, platelet count and mitotic score yielded an area under the curve of 0.96 (95% CI, 0.91-1.0) for BAP1 GM detection among operated PM patients. CONCLUSION: Higher intraoperative tumor burden and lower platelet count and mitotic score are suggestive of BAP1 GMs in surgical PM patients and should prompt germline testing.

De Novo Variants in SPOP Cause Two Clinically Distinct Neurodevelopmental Disorders.

Recurrent somatic variants in SPOP are cancer specific; endometrial and prostate cancers result from gain-of-function and dominant-negative effects toward BET proteins, respectively. By using clinical exome sequencing, we identified six de novo pathogenic missense variants in SPOP in seven individuals with developmental delay and/or intellectual disability, facial dysmorphisms, and congenital anomalies. Two individuals shared craniofacial dysmorphisms, including congenital microcephaly, that were strikingly different from those of the other five individuals, who had (relative) macrocephaly and hypertelorism. We measured the effect of SPOP variants on BET protein amounts in human Ishikawa endometrial cancer cells and patient-derived cell lines because we hypothesized that variants would lead to functional divergent effects on BET proteins. The de novo variants c.362G>A (p.Arg121Gln) and c. 430G>A (p.Asp144Asn), identified in the first two individuals, resulted in a gain of function, and conversely, the c.73A>G (p.Thr25Ala), c.248A>G (p.Tyr83Cys), c.395G>T (p.Gly132Val), and c.412C>T (p.Arg138Cys) variants resulted in a dominant-negative effect. Our findings suggest that these opposite functional effects caused by the variants in SPOP result in two distinct and clinically recognizable syndromic forms of intellectual disability with contrasting craniofacial dysmorphisms.

De Novo Germline and Somatic Variants Convergently Promote Endothelial-to-Mesenchymal Transition in Simplex Brain Arteriovenous Malformation.

[Figure: see text].

Characterisation of protein-truncating and missense variants in PALB2 in 15 768 women from Malaysia and Singapore.

BACKGROUND: Rare protein-truncating variants (PTVs) in partner and localiser of BRCA2 (PALB2) confer increased risk to breast cancer, but relatively few studies have reported the prevalence in South-East Asian populations. Here, we describe the prevalence of rare variants in PALB2 in a population-based study of 7840 breast cancer cases and 7928 healthy Chinese, Malay and Indian women from Malaysia and Singapore, and describe the functional impact of germline missense variants identified in this population. METHODS: Mutation testing was performed on germline DNA (n=15 768) using targeted sequencing panels. The functional impact of missense variants was tested in mouse embryonic stem cell based functional assays. RESULTS: PTVs in PALB2 were found in 0.73% of breast cancer patients and 0.14% of healthy individuals (OR=5.44; 95% CI 2.85 to 10.39, p<0.0001). In contrast, rare missense variants in PALB2 were not associated with increased risk of breast cancer. Whereas PTVs were associated with later stage of presentation and higher-grade tumours, no significant association was observed with missense variants in PALB2. However, two novel rare missense variants (p.L1027R and p.G1043V) produced unstable proteins and resulted in a decrease in homologous recombination-mediated repair of DNA double-strand breaks. CONCLUSION: Despite genetic and lifestyle differences between Asian and other populations, the population prevalence of PALB2 PTVs and associated relative risk of breast cancer, are similar to those reported in European populations.

Screening of CNVs using NGS data improves mutation detection yield and decreases costs in genetic testing for hereditary cancer.

INTRODUCTION: Germline CNVs are important contributors to hereditary cancer. In genetic diagnostics, multiplex ligation-dependent probe amplification (MLPA) is commonly used to identify them. However, MLPA is time-consuming and expensive if applied to many genes, hence many routine laboratories test only a subset of genes of interest. METHODS AND RESULTS: We evaluated a next-generation sequencing (NGS)-based CNV detection tool (DECoN) as first-tier screening to decrease costs and turnaround time and expand CNV analysis to all genes of clinical interest in our diagnostics routine. We used DECoN in a retrospective cohort of 1860 patients where a limited number of genes were previously analysed by MLPA, and in a prospective cohort of 2041 patients, without MLPA analysis. In the retrospective cohort, 6 new CNVs were identified and confirmed by MLPA. In the prospective cohort, 19 CNVs were identified and confirmed by MLPA, 8 of these would have been lost in our previous MLPA-restricted detection strategy. Also, the number of genes tested by MLPA across all samples decreased by 93.0% in the prospective cohort. CONCLUSION: Including an in silico germline NGS CNV detection tool improved our genetic diagnostics strategy in hereditary cancer, both increasing the number of CNVs detected and reducing turnaround time and costs.

Results from London Regional Clinical Genetics services over a 5-year period on germline TP53 testing in women diagnosed with breast cancer at <30 years.

BACKGROUND: The most common cancer diagnosed in germline TP53 pathogenic variant (PV) carriers is premenopausal breast cancer. An increased rate of breast tumour HER2 positivity has been reported in this group. Screening for breast/other cancers is recommended in PV carriers. OBJECTIVES: 1. To assess the frequency of germline TP53 PVs reported diagnostically in women with breast cancer at <30 years of age.2. To evaluate the impact of personal/family history and HER2 status on the likelihood of germline TP53 pathogenic/likely pathogenic variant (PV/LPV) identification. METHODS: Genetic test results from patients undergoing diagnostic germline TP53 tests between 2012 and 2017 in the four London Regional Clinical Genetics Services were reviewed. Clinical/pathology data and family history were extracted from genetics files for women diagnosed with breast cancer at <30 years. RESULTS: The overall germline TP53 PV/LPV variant detection rate was 9/270=3.3% in all women diagnosed with breast cancer at <30 years and 2/171=1.2% in those with no second/subsequent cancer diagnosis or family history of TP53-spectrum cancers. Breast cancers were significantly more likely to be HER2-positive in TP53 PV/LPV carriers than in non-carriers (p=0.00006). CONCLUSIONS: Germline TP53 PVs/LPVs are uncommon among women diagnosed with breast cancer aged <30 years without other relevant personal or family cancer history but have an important clinical impact when identified.

Practice guidelines for BRCA1/2 tumour testing in ovarian cancer.

The purpose of this document is to provide pre-analytical, analytical and post-analytical considerations and recommendations to Canadian clinical laboratories developing, validating and offering next-generation sequencing (NGS)-based BRCA1 and BRCA2 (BRCA1/2) tumour testing in ovarian cancers. This document was drafted by the members of the Canadian College of Medical Geneticists (CCMG) somatic BRCA Ad Hoc Working Group, and representatives from the Canadian Association of Pathologists. The document was circulated to the CCMG members for comment. Following incorporation of feedback, this document has been approved by the CCMG board of directors. The CCMG is a Canadian organisation responsible for certifying medical geneticists and clinical laboratory geneticists, and for establishing professional and ethical standards for clinical genetics services in Canada. The current CCMG Practice Guidelines were developed as a resource for clinical laboratories in Canada; however, they are not inclusive of all information laboratories should consider in the validation and use of NGS for BRCA1/2 tumour testing in ovarian cancers.

Rising of LOXHD1 as a signature causative gene of down-sloping hearing loss in people in their teens and 20s.

BACKGROUND: Down-sloping sensorineural hearing loss (SNHL) in people in their teens and 20s hampers efficient learning and communication and in-depth social interactions. Nonetheless, its aetiology remains largely unclear, with the exception of some potential causative genes, none of which stands out especially in people in their teens and 20s. Here, we examined the role and genotype-phenotype correlation of lipoxygenase homology domain 1 (LOXHD1) in down-sloping SNHL through a cohort study. METHODS: Based on the Seoul National University Bundang Hospital (SNUBH) genetic deafness cohort, in which the patients show varying degrees of deafness and different onset ages (n=1055), we have established the 'SNUBH Teenager-Young Adult Down-sloping SNHL' cohort (10-35 years old) (n=47), all of whom underwent exome sequencing. Three-dimensional molecular modelling, minigene splicing assay and short tandem repeat marker genotyping were performed, and medical records were reviewed. RESULTS: LOXHD1 accounted for 33.3% of all genetically diagnosed cases of down-sloping SNHL (n=18) and 12.8% of cases in the whole down-sloping SNHL cohort (n=47) of young adults. We identified a potential common founder allele, as well as an interesting genotype-phenotype correlation. We also showed that transcript 6 is necessary and probably sufficient for normal hearing. CONCLUSIONS: LOXHD1 exceeds other genes in its contribution to down-sloping SNHL in young adults, rising as a signature causative gene, and shows a potential but interesting genotype-phenotype correlation.