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1.
Nat Commun ; 15(1): 4893, 2024 Jun 07.
Article in English | MEDLINE | ID: mdl-38849340

ABSTRACT

Amyotrophic lateral sclerosis (ALS) is a debilitating motor neuron disease and lacks effective disease-modifying treatments. This study utilizes a comprehensive multiomic approach to investigate the early and sex-specific molecular mechanisms underlying ALS. By analyzing the prefrontal cortex of 51 patients with sporadic ALS and 50 control subjects, alongside four transgenic mouse models (C9orf72-, SOD1-, TDP-43-, and FUS-ALS), we have uncovered significant molecular alterations associated with the disease. Here, we show that males exhibit more pronounced changes in molecular pathways compared to females. Our integrated analysis of transcriptomes, (phospho)proteomes, and miRNAomes also identified distinct ALS subclusters in humans, characterized by variations in immune response, extracellular matrix composition, mitochondrial function, and RNA processing. The molecular signatures of human subclusters were reflected in specific mouse models. Our study highlighted the mitogen-activated protein kinase (MAPK) pathway as an early disease mechanism. We further demonstrate that trametinib, a MAPK inhibitor, has potential therapeutic benefits in vitro and in vivo, particularly in females, suggesting a direction for developing targeted ALS treatments.


Subject(s)
Amyotrophic Lateral Sclerosis , Disease Models, Animal , MAP Kinase Signaling System , Mice, Transgenic , Amyotrophic Lateral Sclerosis/genetics , Amyotrophic Lateral Sclerosis/drug therapy , Amyotrophic Lateral Sclerosis/metabolism , Humans , Female , Animals , Male , Mice , MAP Kinase Signaling System/drug effects , Pyridones/pharmacology , Pyridones/therapeutic use , RNA-Binding Protein FUS/metabolism , RNA-Binding Protein FUS/genetics , Prefrontal Cortex/metabolism , Transcriptome , Superoxide Dismutase-1/genetics , Superoxide Dismutase-1/metabolism , DNA-Binding Proteins/metabolism , DNA-Binding Proteins/genetics , Middle Aged , MicroRNAs/genetics , MicroRNAs/metabolism , C9orf72 Protein/genetics , C9orf72 Protein/metabolism , Sex Characteristics , Aged , Sex Factors , Pyrimidinones
2.
NPJ Parkinsons Dis ; 10(1): 85, 2024 Apr 15.
Article in English | MEDLINE | ID: mdl-38622158

ABSTRACT

The genetic loci implicated in familial Parkinson's disease (PD) have limited generalizability to the Indian PD population. We tested mutations and the frequency of known mutations in the SNCA gene in a PD cohort from India. We selected 298 PD cases and 301 age-matched controls for targeted resequencing (before QC), along with 363 PD genomes of Indian ancestry and 1029 publicly available whole genomes from India as healthy controls (IndiGenomes), to determine the frequency of monogenic SNCA mutations. The raw sequence reads were analyzed using an in-house analysis pipeline, allowing the detection of small variants and structural variants using Manta. The in-depth analysis of the SNCA locus did not identify missense or structural variants, including previously identified SNCA mutations, in the Indian population. The familial forms of SNCA gene variants do not play a major role in the Indian PD population and this warrants further research in the under-represented population.

3.
Mov Disord ; 2024 Apr 08.
Article in English | MEDLINE | ID: mdl-38586902

ABSTRACT

BACKGROUND: Most Parkinson's disease (PD) loci have shown low prevalence in the Indian population, highlighting the need for further research. OBJECTIVE: The aim of this study was to characterize a novel phosphatase tensin homolog-induced serine/threonine kinase 1 (PINK1) mutation causing PD in an Indian family. METHODS: Exome sequencing of a well-characterized Indian family with PD. A novel PINK1 mutation was studied by in silico modeling using AlphaFold2, expression of mutant PINK1 in human cells depleted of functional endogenous PINK1, followed by quantitative image analysis and biochemical assessment. RESULTS: We identified a homozygous chr1:20648535-20648535 T>C on GRCh38 (p.F385S) mutation in exon 6 of PINK1, which was absent in 1029 genomes from India and in other known databases. PINK1 F385S lies within the highly conserved Deutsche Forschungsgemeinschaft (DFG) motif, destabilizes its active state, and impairs phosphorylation of ubiquitin at serine 65 and proper engagement of parkin upon mitochondrial depolarization. CONCLUSIONS: We characterized a novel nonconservative mutation in the DFG motif of PINK1, which causes loss of its ubiquitin kinase activity and inhibition of mitophagy. © 2024 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

4.
Nat Genet ; 2024 Apr 29.
Article in English | MEDLINE | ID: mdl-38684900

ABSTRACT

Despite linkage to chromosome 16q in 1996, the mutation causing spinocerebellar ataxia type 4 (SCA4), a late-onset sensory and cerebellar ataxia, remained unknown. Here, using long-read single-strand whole-genome sequencing (LR-GS), we identified a heterozygous GGC-repeat expansion in a large Utah pedigree encoding polyglycine (polyG) in zinc finger homeobox protein 3 (ZFHX3), also known as AT-binding transcription factor 1 (ATBF1). We queried 6,495 genome sequencing datasets and identified the repeat expansion in seven additional pedigrees. Ultrarare DNA variants near the repeat expansion indicate a common distant founder event in Sweden. Intranuclear ZFHX3-p62-ubiquitin aggregates were abundant in SCA4 basis pontis neurons. In fibroblasts and induced pluripotent stem cells, the GGC expansion led to increased ZFHX3 protein levels and abnormal autophagy, which were normalized with small interfering RNA-mediated ZFHX3 knockdown in both cell types. Improving autophagy points to a therapeutic avenue for this novel polyG disease. The coding GGC-repeat expansion in an extremely G+C-rich region was not detectable by short-read whole-exome sequencing, which demonstrates the power of LR-GS for variant discovery.

5.
Lancet Neurol ; 23(6): 603-614, 2024 Jun.
Article in English | MEDLINE | ID: mdl-38614108

ABSTRACT

BACKGROUND: Parkinson's disease is a progressive neurodegenerative disorder with multifactorial causes, among which genetic risk factors play a part. The RAB GTPases are regulators and substrates of LRRK2, and variants in the LRRK2 gene are important risk factors for Parkinson's disease. We aimed to explore genetic variability in RAB GTPases within cases of familial Parkinson's disease. METHODS: We did whole-exome sequencing in probands from families in Canada and Tunisia with Parkinson's disease without a genetic cause, who were recruited from the Centre for Applied Neurogenetics (Vancouver, BC, Canada), an international consortium that includes people with Parkinson's disease from 36 sites in 24 countries. 61 RAB GTPases were genetically screened, and candidate variants were genotyped in relatives of the probands to assess disease segregation by linkage analysis. Genotyping was also done to assess variant frequencies in individuals with idiopathic Parkinson's disease and controls, matched for age and sex, who were also from the Centre for Applied Neurogenetics but unrelated to the probands or each other. All participants were aged 18 years or older. The sequencing and genotyping findings were validated by case-control association analyses using bioinformatic data obtained from publicly available clinicogenomic databases (AMP-PD, GP2, and 100 000 Genomes Project) and a private German clinical diagnostic database (University of Tübingen). Clinical and pathological findings were summarised and haplotypes were determined. In-vitro studies were done to investigate protein interactions and enzyme activities. FINDINGS: Between June 1, 2010, and May 31, 2017, 130 probands from Canada and Tunisia (47 [36%] female and 83 [64%] male; mean age 72·7 years [SD 11·7; range 38-96]; 109 White European ancestry, 18 north African, two east Asian, and one Hispanic] underwent whole-exome sequencing. 15 variants in RAB GTPase genes were identified, of which the RAB32 variant c.213C>G (Ser71Arg) cosegregated with autosomal dominant Parkinson's disease in three families (nine affected individuals; non-parametric linkage Z score=1·95; p=0·03). 2604 unrelated individuals with Parkinson's disease and 344 matched controls were additionally genotyped, and five more people originating from five countries (Canada, Italy, Poland, Turkey, and Tunisia) were identified with the RAB32 variant. From the database searches, in which 6043 individuals with Parkinson's disease and 62 549 controls were included, another eight individuals were identified with the RAB32 variant from four countries (Canada, Germany, UK, and USA). Overall, the association of RAB32 c.213C>G (Ser71Arg) with Parkinson's disease was significant (odds ratio [OR] 13·17, 95% CI 2·15-87·23; p=0·0055; I2=99·96%). In the people who had the variant, Parkinson's disease presented at age 54·6 years (SD 12·75, range 31-81, n=16), and two-thirds had a family history of parkinsonism. RAB32 Ser71Arg heterozygotes shared a common haplotype, although penetrance was incomplete. Findings in one individual at autopsy showed sparse neurofibrillary tangle pathology in the midbrain and thalamus, without Lewy body pathology. In functional studies, RAB32 Arg71 activated LRRK2 kinase to a level greater than RAB32 Ser71. INTERPRETATION: RAB32 Ser71Arg is a novel genetic risk factor for Parkinson's disease, with reduced penetrance. The variant was found in individuals with Parkinson's disease from multiple ethnic groups, with the same haplotype. In-vitro assays show that RAB32 Arg71 activates LRRK2 kinase, which indicates that genetically distinct causes of familial parkinsonism share the same mechanism. The discovery of RAB32 Ser71Arg also suggests several genetically inherited causes of Parkinson's disease originated to control intracellular immunity. This shared aetiology should be considered in future translational research, while the global epidemiology of RAB32 Ser71Arg needs to be assessed to inform genetic counselling. FUNDING: National Institutes of Health, the Canada Excellence Research Chairs program, Aligning Science Across Parkinson's, the Michael J Fox Foundation for Parkinson's Research, and the UK Medical Research Council.


Subject(s)
Parkinson Disease , rab GTP-Binding Proteins , Humans , Female , Male , Parkinson Disease/genetics , rab GTP-Binding Proteins/genetics , Middle Aged , Aged , Genetic Linkage/genetics , Adult , Canada/epidemiology , Leucine-Rich Repeat Serine-Threonine Protein Kinase-2/genetics , Tunisia , Genetic Predisposition to Disease/genetics , Exome Sequencing , Case-Control Studies , Genotype
6.
NPJ Genom Med ; 9(1): 20, 2024 Mar 14.
Article in English | MEDLINE | ID: mdl-38485733

ABSTRACT

In the era of precision medicine, genome sequencing (GS) has become more affordable and the importance of genomics and multi-omics in clinical care is increasingly being recognized. However, how to scale and effectively implement GS on an institutional level remains a challenge for many. Here, we present Genome First and Ge-Med, two clinical implementation studies focused on identifying the key pillars and processes that are required to make routine GS and predictive genomics a reality in the clinical setting. We describe our experience and lessons learned for a variety of topics including test logistics, patient care processes, data reporting, and infrastructure. Our model of providing clinical care and comprehensive genomic analysis from a single source may be used by other centers with a similar structure to facilitate the implementation of omics-based personalized health concepts in medicine.

7.
Brain ; 2024 Feb 22.
Article in English | MEDLINE | ID: mdl-38386308

ABSTRACT

Neurodevelopmental disorders are major indications for genetic referral and have been linked to more than 1,500 loci including genes encoding transcriptional regulators. The dysfunction of transcription factors often results in characteristic syndromic presentations, however, at least half of these patients lack a genetic diagnosis. The implementation of machine learning approaches has the potential to aid in the identification of new disease genes and delineate associated phenotypes. Next generation sequencing was performed in seven affected individuals with neurodevelopmental delay and dysmorphic features. Clinical characterization included reanalysis of available neuroimaging datasets and 2D portrait image analysis with GestaltMatcher. The functional consequences of ZSCAN10 loss were modelled in mouse embryonic stem cells (mESC), including a knock-out and a representative ZSCAN10 protein truncating variant. These models were characterized by gene expression and Western blot analyses, chromatin immunoprecipitation and quantitative PCR (ChIP-qPCR), and immunofluorescence staining. Zscan10 knockout mouse embryos were generated and phenotyped. We prioritized bi-allelic ZSCAN10 loss-of-function variants in seven affected individuals from five unrelated families as the underlying molecular cause. RNA-Seq analyses in Zscan10-/- mESCs indicated dysregulation of genes related to stem cell pluripotency. In addition, we established in mESCs the loss-of-function mechanism for a representative human ZSCAN10 protein truncating variant by showing alteration of its expression levels and subcellular localization, interfering with its binding to DNA enhancer targets. Deep phenotyping revealed global developmental delay, facial asymmetry, and malformations of the outer ear as consistent clinical features. Cerebral MRI showed dysplasia of the semicircular canals as an anatomical correlate of sensorineural hearing loss. Facial asymmetry was confirmed as a clinical feature by GestaltMatcher and was recapitulated in the Zscan10 mouse model along with inner and outer ear malformations. Our findings provide evidence of a novel syndromic neurodevelopmental disorder caused by bi-allelic loss-of-function variants in ZSCAN10.

8.
medRxiv ; 2024 Jan 18.
Article in English | MEDLINE | ID: mdl-38293014

ABSTRACT

Background: Parkinson's disease (PD) is a progressive neurodegenerative disorder. Mendelian forms have revealed multiple genes, with a notable emphasis on membrane trafficking; RAB GTPases play an important role in PD as a subset are both regulators and substrates of LRRK2 protein kinase. To explore the role of RAB GTPases in PD, we undertook a comprehensive examination of their genetic variability in familial PD. Methods: Affected probands from 130 multi-incident PD families underwent whole-exome sequencing and genotyping, Potential pathogenic variants in 61 RAB GTPases were genotyped in relatives to assess disease segregation. These variants were also genotyped in a larger case-control series, totaling 3,078 individuals (2,734 with PD). The single most significant finding was subsequently validated within genetic data (6,043 with PD). Clinical and pathologic findings were summarized for gene-identified patients, and haplotypes were constructed. In parallel, wild-type and mutant RAB GTPase structural variation, protein interactions, and resultant enzyme activities were assessed. Findings: We found RAB32 c.213C>G (Ser71Arg) to co-segregate with autosomal dominant parkinsonism in three multi-incident families. RAB32 Ser71Arg was also significantly associated with PD in case-control samples: genotyping and database searches identified thirteen more patients with the same variant that was absent in unaffected controls. Notably, RAB32 Ser71Arg heterozygotes share a common haplotype. At autopsy, one patient had sparse neurofibrillary tangle pathology in the midbrain and thalamus, without Lewy body pathology. In transfected cells the RAB32 Arg71 was twice as potent as Ser71 wild type to activate LRRK2 kinase. Interpretation: Our study provides unequivocal evidence to implicate RAB32 Ser71Arg in PD. Functional analysis demonstrates LRRK2 kinase activation. We provide a mechanistic explanation to expand and unify the etiopathogenesis of monogenic PD. Funding: National Institutes of Health, the Canada Excellence Research Chairs program, Aligning Science Across Parkinson's, the Michael J. Fox Foundation for Parkinson's Research, and the UK Medical Research Council.

9.
Genes (Basel) ; 15(1)2024 Jan 22.
Article in English | MEDLINE | ID: mdl-38275617

ABSTRACT

The potential of genome sequencing (GS), which allows detection of almost all types of genetic variation across nearly the entire genome of an individual, greatly expands the possibility for diagnosing genetic disorders. The opportunities provided with this single test are enticing to researchers and clinicians worldwide for human genetic research as well as clinical application. Multiple studies have highlighted the advantages of GS for genetic variant discovery, emphasizing its added value for routine clinical use. We have implemented GS as first-line genetic testing for patients with rare diseases. Here, we report on our experiences in establishing GS as a reliable diagnostic method for almost all types of genetic disorders, from validating diagnostic accuracy of sequencing pipelines to clinical implementation in routine practice.


Subject(s)
Genetic Testing , Genome , Humans , Genetic Testing/methods , Base Sequence , Chromosome Mapping , Whole Genome Sequencing/methods
10.
J Med Genet ; 61(2): 186-195, 2024 Jan 19.
Article in English | MEDLINE | ID: mdl-37734845

ABSTRACT

PURPOSE: Genome sequencing (GS) is expected to reduce the diagnostic gap in rare disease genetics. We aimed to evaluate a scalable framework for genome-based analyses 'beyond the exome' in regular care of patients with inherited retinal degeneration (IRD) or inherited optic neuropathy (ION). METHODS: PCR-free short-read GS was performed on 1000 consecutive probands with IRD/ION in routine diagnostics. Complementary whole-blood RNA-sequencing (RNA-seq) was done in a subset of 74 patients. An open-source bioinformatics analysis pipeline was optimised for structural variant (SV) calling and combined RNA/DNA variation interpretation. RESULTS: A definite genetic diagnosis was established in 57.4% of cases. For another 16.7%, variants of uncertain significance were identified in known IRD/ION genes, while the underlying genetic cause remained unresolved in 25.9%. SVs or alterations in non-coding genomic regions made up for 12.7% of the observed variants. The RNA-seq studies supported the classification of two unclear variants. CONCLUSION: GS is feasible in clinical practice and reliably identifies causal variants in a substantial proportion of individuals. GS extends the diagnostic yield to rare non-coding variants and enables precise determination of SVs. The added diagnostic value of RNA-seq is limited by low expression levels of the major IRD disease genes in blood.


Subject(s)
Exome , Eye Diseases , Humans , Prospective Studies , Base Sequence , RNA , Eye Diseases/diagnosis , Eye Diseases/genetics
11.
Pancreatology ; 23(8): 957-963, 2023 Dec.
Article in English | MEDLINE | ID: mdl-37949771

ABSTRACT

BACKGROUND: Genetic predisposition is crucial in the pathogenesis of early-onset chronic pancreatitis (CP). So far, several genetic alterations have been identified as risk factors, predominantly in genes encoding digestive enzymes. However, many early-onset CP cases have no identified underlying cause. Chymotrypsins are a family of serine proteases that can cleave trypsinogen and lead to its degradation. Because genetic alterations in the chymotrypsins CTRC, CTRB1, and CTRB2 are associated with CP, we genetically and functionally investigated chymotrypsin-like protease (CTRL) as a potential risk factor. METHODS: We screened 1005 non-alcoholic CP patients and 1594 controls for CTRL variants by exome sequencing. We performed Western blots and activity assays to analyse secretion and proteolytic activity. We measured BiP mRNA expression to investigate the potential impact of identified alterations on endoplasmic reticulum (ER) stress. RESULTS: We identified 13 heterozygous non-synonymous CTRL variants: five exclusively in patients and three only in controls. Functionality was unchanged in 6/13 variants. Four alterations showed normal secretion but reduced (p.G20S, p.G56S, p.G61S) or abolished (p.S208F) activity. Another three variants (p.C201Y, p.G215R and p.C220G) were not secreted and already showed reduced or no activity intracellularly. However, intracellular retention did not lead to ER stress. CONCLUSION: We identified several CTRL variants, some showing potent effects on protease function and secretion. We observed these effects in variants found in patients and controls, and CTRL loss-of-function variants were not significantly more common in patients than controls. Therefore, CTRL is unlikely to play a relevant role in the development of CP.


Subject(s)
Chymases , Pancreatitis, Chronic , Humans , Chymases/genetics , Genetic Predisposition to Disease , Mutation , Pancreatitis, Chronic/genetics , Pancreatitis, Chronic/metabolism , Risk Factors
12.
Front Genet ; 14: 1214736, 2023.
Article in English | MEDLINE | ID: mdl-37671045

ABSTRACT

Genetic heterogeneity makes it difficult to identify the causal genes for hearing loss. Studies from previous decades have mapped numerous genetic loci, providing critical supporting evidence for gene discovery studies. Despite widespread sequencing accessibility, many historically mapped loci remain without a causal gene. The DFNA33 locus was mapped in 2009 and coincidentally contains ATP11A, a gene recently associated with autosomal dominant hearing loss and auditory neuropathy type 2. In a rare opportunity, we genome-sequenced a member of the original family to determine whether the DFNA33 locus may also be assigned to ATP11A. We identified a deep intronic variant in ATP11A that showed evidence of functionally normal splicing. Furthermore, we re-assessed haplotypes from the originally published DFNA33 family and identified two double recombination events and one triple recombination event in the pedigree, a highly unlikely occurrence, especially at this scale. This brief research report also serves as a call to the community to revisit families who have previously been involved in gene mapping studies, provide closure, and resolve these historical loci.

13.
EBioMedicine ; 96: 104797, 2023 Oct.
Article in English | MEDLINE | ID: mdl-37716236

ABSTRACT

BACKGROUND: Genomic characterisation has led to an improved understanding of adult melanoma. However, the aetiology of melanoma in children is still unclear and identifying the correct diagnosis and therapeutic strategies remains challenging. METHODS: Exome sequencing of matched tumour-normal pairs from 26 paediatric patients was performed to study the mutational spectrum of melanomas. The cohort was grouped into different categories: spitzoid melanoma (SM), conventional melanoma (CM), and other melanomas (OT). FINDINGS: In all patients with CM (n = 10) germline variants associated with melanoma were found in low to moderate melanoma risk genes: in 8 patients MC1R variants, in 2 patients variants in MITF, PTEN and BRCA2. Somatic BRAF mutations were detected in 60% of CMs, homozygous deletions of CDKN2A in 20%, TERTp mutations in 30%. In the SM group (n = 12), 5 patients carried at least one MC1R variant; somatic BRAF mutations were detected in 8.3%, fusions in 25% of the cases. No SM showed a homozygous CDKN2A deletion nor a TERTp mutation. In 81.8% of the CM/SM cases the UV damage signatures SBS7 and/or DBS1 were detected. The patient with melanoma arising in giant congenital nevus (CNM) demonstrated the characteristic NRAS Q61K mutation. INTERPRETATION: UV-radiation and MC1R germline variants are risk factors in the development of conventional and spitzoid paediatric melanomas. Paediatric CMs share genomic similarities with adult CMs while the SMs differ genetically from the CM group. Consistent genetic characterization of all paediatric melanomas will potentially lead to better subtype differentiation, treatment, and prevention in the future. FUNDING: Found in Acknowledgement.

15.
Eur J Hum Genet ; 31(10): 1139-1146, 2023 10.
Article in English | MEDLINE | ID: mdl-37507557

ABSTRACT

The prevalence of pathogenic and likely pathogenic (P/LP) variants in genes associated with cancer predisposition syndromes (CPS) is estimated to be 8-18% for paediatric cancer patients. In more than half of the carriers, the family history is unsuspicious for CPS. Therefore, broad genetic testing could identify germline predisposition in additional children with cancer resulting in important implications for themselves and their families. We thus evaluated clinical trio genome sequencing (TGS) in a cohort of 72 paediatric patients with solid cancers other than retinoblastoma or CNS-tumours. The most prevalent cancer types were sarcoma (n = 26), neuroblastoma (n = 15), and nephroblastoma (n = 10). Overall, P/LP variants in CPS genes were identified in 18.1% of patients (13/72) and P/LP variants in autosomal-dominant CPS genes in 9.7% (7/72). Genetic evaluation would have been recommended for the majority of patients with P/LP variants according to the Jongmans criteria. Four patients (5.6%, 4/72) carried P/LP variants in autosomal-dominant genes known to be associated with their tumour type. With the immediate information on variant inheritance, TGS facilitated the identification of a de novo P/LP in NF1, a gonadosomatic mosaic in WT1 and two pathogenic variants in one patient (DICER1 and PALB2). TGS allows a more detailed characterization of structural variants with base-pair resolution of breakpoints which can be relevant for the interpretation of copy number variants. Altogether, TGS allows comprehensive identification of children with a CPS and supports the individualised clinical management of index patients and high-risk relatives.


Subject(s)
Genetic Predisposition to Disease , Neoplasms , Humans , Child , Germ-Line Mutation , Neoplasms/genetics , Genetic Testing/methods , Genotype , Ribonuclease III/genetics , DEAD-box RNA Helicases/genetics
17.
Mol Genet Genomic Med ; 11(6): e2151, 2023 06.
Article in English | MEDLINE | ID: mdl-36760167

ABSTRACT

BACKGROUND: Lynch syndrome is one of the most common cancer predisposition syndromes. It is caused by inherited changes in the mismatch repair pathway. With current diagnostic approaches, a causative genetic variant can be found in less than 50% of cases. A correct diagnosis is important for ensuring that an appropriate surveillance program is used and that additional high-risk family members are identified. METHODS: We used clinical genome sequencing on DNA from blood and subsequent transcriptome sequencing for confirmation. Data were analyzed using the megSAP pipeline and classified according to basic criteria in diagnostic laboratories. Segregation analyses in family members were conducted via breakpoint PCR. RESULTS: We present a family with the clinical diagnosis of Lynch syndrome in which standard diagnostic tests, such as panel or exome sequencing, were unable to detect the underlying genetic variant. Genome sequencing in the index patient confirmed the previous diagnostic results and identified an additional complex rearrangement with intronic breakpoints involving MLH1 and its neighboring gene LRRFIP2. The previously undetected structural variant was classified as medically relevant. Segregation analysis in the family identified additional at-risk individuals which were offered intensified cancer screening. DISCUSSION AND CONCLUSIONS: This case illustrates the advantages of clinical genome sequencing in detecting structural variants compared with current diagnostic approaches. Although structural variants are rare in Lynch syndrome families, they seem to be underreported, in part because of technical challenges. Clinical genome sequencing offers a comprehensive genetic characterization detecting a wide range of genetic variants.


Subject(s)
Colorectal Neoplasms, Hereditary Nonpolyposis , Humans , Colorectal Neoplasms, Hereditary Nonpolyposis/diagnosis , Colorectal Neoplasms, Hereditary Nonpolyposis/genetics , Colorectal Neoplasms, Hereditary Nonpolyposis/metabolism , Base Sequence , Introns , MutL Protein Homolog 1/genetics , MutL Protein Homolog 1/metabolism
18.
J Med Genet ; 60(1): 48-56, 2023 01.
Article in English | MEDLINE | ID: mdl-34740919

ABSTRACT

BACKGROUND: Fetal akinesia (FA) results in variable clinical presentations and has been associated with more than 166 different disease loci. However, the underlying molecular cause remains unclear in many individuals. We aimed to further define the set of genes involved. METHODS: We performed in-depth clinical characterisation and exome sequencing on a cohort of 23 FA index cases sharing arthrogryposis as a common feature. RESULTS: We identified likely pathogenic or pathogenic variants in 12 different established disease genes explaining the disease phenotype in 13 index cases and report 12 novel variants. In the unsolved families, a search for recessive-type variants affecting the same gene was performed; and in five affected fetuses of two unrelated families, a homozygous loss-of-function variant in the kinesin family member 21A gene (KIF21A) was found. CONCLUSION: Our study underlines the broad locus heterogeneity of FA with well-established and atypical genotype-phenotype associations. We describe KIF21A as a new factor implicated in the pathogenesis of severe neurogenic FA sequence with arthrogryposis of multiple joints, pulmonary hypoplasia and facial dysmorphisms. This hypothesis is further corroborated by a recent report on overlapping phenotypes observed in Kif21a null piglets.


Subject(s)
Arthrogryposis , Humans , Animals , Swine , Mutation/genetics , Arthrogryposis/genetics , Arthrogryposis/pathology , Loss of Heterozygosity , Fetus , Phenotype , Pedigree , Kinesins/genetics
19.
J Neurol ; 270(3): 1501-1511, 2023 Mar.
Article in English | MEDLINE | ID: mdl-36411388

ABSTRACT

BACKGROUND: Genetic variants are considered to have a crucial impact on the occurrence of ischemic stroke. In clinical routine, the diagnostic value of next-generation sequencing (NGS) in the medical clarification of acute juvenile stroke has not been investigated so far. MATERIAL AND METHODS: We analyzed an exome-based gene panel of 349 genes in 172 clinically well-characterized patients with magnetic resonance imaging (MRI)-proven, juvenile (age ≤ 55 years), ischemic stroke admitted to a single comprehensive stroke center. RESULTS: Monogenetic diseases causing ischemic stroke were observed in five patients (2.9%): In three patients with lacunar stroke (1.7%), we identified pathogenic variants in NOTCH3 causing cerebral autosomal-dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL). Hence, CADASIL was identified at a frequency of 12.5% in the lacunar stroke subgroup. Further, in two male patients (1.2%) suffering from lacunar and cardioembolic stroke, pathogenic variants in GLA causing Fabry's disease were present. Additionally, genetic variants in monogenetic diseases lacking impact on stroke occurrence, variants of unclear significance (VUS) in monogenetic diseases, and (cardiovascular-) risk genes in ischemic stroke were observed in a total of 15 patients (15.7%). CONCLUSION: Genetic screening for Fabry's disease in cardioembolic and lacunar stroke as well as CADASIL in lacunar stroke might be beneficial in routine medical work-up of acute juvenile ischemic stroke.


Subject(s)
CADASIL , Fabry Disease , Ischemic Stroke , Stroke, Lacunar , Stroke , Humans , Male , Middle Aged , CADASIL/diagnostic imaging , CADASIL/genetics , Stroke, Lacunar/genetics , Ischemic Stroke/genetics , Fabry Disease/genetics , Exome , Receptor, Notch3/genetics , Stroke/diagnostic imaging , Stroke/genetics , Receptors, Notch/genetics , Magnetic Resonance Imaging , Mutation/genetics
20.
Med Genet ; 35(2): 91-104, 2023 Jun.
Article in English | MEDLINE | ID: mdl-38840862

ABSTRACT

The rapid and dynamic implementation of Next-Generation Sequencing (NGS)-based assays has revolutionized genetic testing, and in the near future, nearly all molecular alterations of the human genome will be diagnosable via massive parallel sequencing. While this progress will further corroborate the central role of human genetics in the multidisciplinary management of patients with genetic disorders, it must be accompanied by quality assurance measures in order to allow the safe and optimal use of knowledge ascertained from genome diagnostics. To achieve this, several valuable tools and guidelines have been developed to support the quality of genome diagnostics. In this paper, authors with experience in diverse aspects of genomic analysis summarize the current status of quality assurance in genome diagnostics, with the aim of facilitating further standardization and quality improvement in one of the core competencies of the field.

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