Molecular Diagnosis of Hereditary Neuropathies by Whole Exome Sequencing and Expanding the Phenotype Spectrum

Background: Inherited peripheral neuropathies (IPNs) are a group of neuropathies affecting peripheral motor and sensory neurons. Charcot-Marie-Tooth (CMT) disease is the most common disease in this group. With recent advances in next-generation sequencing (NGS) technologies, more than 100 genes have been implicated for different types of CMT and other clinically and genetically inherited neuropathies. There are also a number of genes where neuropathy is a major feature of the disease such as spinocerebellar ataxia (SCA) and hereditary spastic paraplegia (HSP). We aimed to determine the genetic causes underlying IPNs in Iranian families. Methods: We performed whole exome sequencing (WES) for 58 PMP22 deletion-/duplication-negative unrelated Iranian patients with a spectrum of phenotypes and with a preliminary diagnosis of hereditary neuropathies. Results: Twenty-seven (46.6%) of the cases were genetically diagnosed with pathogenic or likely pathogenic variants. In this study, we identified genetically strong variants within genes not previously linked to any established disease phenotype in five (8.6%) patients. Conclusion: Our results highlight the advantage of using WES for genetic diagnosis in highly heterogeneous diseases such as IPNs. Moreover, functional analysis is required for novel and uncertain variants.

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B.06 Whole exome sequencing in genetic ataxias associated with cerebellar atrophy: the Canadian experience

Canadian Journal of Neurological Sciences / Journal Canadien des Sciences Neurologiques ◽

10.1017/cjn.2019.95 ◽

2019 ◽

Vol 46 (s1) ◽

pp. S11

Author(s):

L Gauquelin ◽

T Hartley ◽

M Tarnopolsky ◽

DA Dyment ◽

B Brais ◽

...

Keyword(s):

Exome Sequencing ◽

Whole Exome Sequencing ◽

Diagnostic Yield ◽

Genetic Diseases ◽

Genetic Diagnosis ◽

Cerebellar Atrophy ◽

Clinical Findings ◽

Disease Genes ◽

Pathogenic Variants ◽

Whole Exome

Background: Cerebellar atrophy is characterized by loss of cerebellar tissue, with evidence on brain imaging of enlarged interfolial spaces compared to the foliae. Genetic ataxias associated with cerebellar atrophy are a heterogeneous group of disorders. We investigated the prevalence in Canada and the diagnostic yield of whole exome sequencing (WES) for this group of conditions. Methods: Between 2011 and 2017, WES was performed in 91 participants with cerebellar atrophy as part of one of two national research programs, Finding of Rare Genetic Disease Genes (FORGE) or Enhanced Care for Rare Genetic Diseases in Canada (Care4Rare). Results: A genetic diagnosis was established in 58% of cases (53/91). Pathogenic variants were found in 24 known genes, providing a diagnosis for 46/53 participants (87%), and in four novel genes, accounting for 7/53 cases (13%). 38/91 cases (42%) remained unsolved. The most common diagnoses were channelopathies in 12/53 patients (23%) and mitochondrial disorders in 9/53 (17%). Inheritance was autosomal recessive in the majority of cases. Additional clinical findings provided useful clues to some of the diagnoses. Conclusions: This is the first report on the prevalence of genetic ataxias associated with cerebellar atrophy in Canada, and the utility of WES for this group of conditions.

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Genomic profiling of 553 uncharacterized neurodevelopment patients reveals a high proportion of recessive pathogenic variant carriers in an outbred population

10.1101/675868 ◽

2019 ◽

Author(s):

Youngha Lee ◽

Soojin Park ◽

Jin Sook Lee ◽

Soo Yeon Kim ◽

Jaeso Cho ◽

...

Keyword(s):

Exome Sequencing ◽

Whole Exome Sequencing ◽

Genetic Diagnosis ◽

Pathogenic Variant ◽

Mendelian Disease ◽

Loss Of Function ◽

Variant Discovery ◽

Pathogenic Variants ◽

Whole Exome ◽

Neurodevelopmental Problems

AbstractBackgroundA substantial portion of Mendelian disease patients suffers from genetic variants that are inherited in a recessive manner. A precise understanding of pathogenic recessive variants in a population would assist in pre-screening births of such patients. However, a systematic understanding of the contribution of recessive variants to Mendelian diseases is still lacking.MethodsGenetic diagnosis and variant discovery of 553 undiagnosed Korean patients with complex neurodevelopmental problems (KND for Korean NeuroDevelopmental cohort) were performed using whole exome sequencing of patients and their parents. Pathogenic variants were selected and evaluated based on a comparison to patient symptoms and genetic properties of the variants were analyzed.ResultsDisease-causing variants, including newly discovered variants, were identified in in 57.5% of the probands of the KND cohort. Of the 553 patients, 47.4% harbored variants that were previously reported as being pathogenic, and 35.1% of the previous reported pathogenic variants were inherited in a recessive manner. Genes that cause recessive disorders tend to be less constrained by loss-of-function variants and enriched in metabolic and mitochondrial pathways. This observation was applied to an estimation that approximately 1 in 17 healthy Korean individuals carry at least one of these pathogenic variants that develop severe neurodevelopmental problems in a recessive manner. Furthermore, the feasibility of these genes for carrier screening was evaluated.ConclusionsWe suggest that the odds are high for healthy individuals carrying a potentially pathogenic variant, and its genetic properties. Our results will serve as a foundation for recessive variant screening to reduce occurrences of rare Mendelian disease patients. Additionally, our results highlight the utility and necessity of whole exome sequencing-based diagnostics for improving patient care in a country with a centralized medical system.

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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.

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Exome sequencing in paediatric patients with movement disorders

Orphanet Journal of Rare Diseases ◽

10.1186/s13023-021-01688-6 ◽

2021 ◽

Vol 16 (1) ◽

Author(s):

Anna Ka-Yee Kwong ◽

Mandy Ho-Yin Tsang ◽

Jasmine Lee-Fong Fung ◽

Christopher Chun-Yu Mak ◽

Kate Lok-San Chan ◽

...

Keyword(s):

Exome Sequencing ◽

Whole Exome Sequencing ◽

Movement Disorders ◽

Rare Variants ◽

Diagnostic Yield ◽

Neurological Diseases ◽

Genetic Diagnosis ◽

Potential Treatment ◽

Paediatric Patients ◽

Whole Exome

Abstract Background Movement disorders are a group of heterogeneous neurological diseases including hyperkinetic disorders with unwanted excess movements and hypokinetic disorders with reduction in the degree of movements. The objective of our study is to investigate the genetic etiology of a cohort of paediatric patients with movement disorders by whole exome sequencing and to review the potential treatment implications after a genetic diagnosis. Results We studied a cohort of 31 patients who have paediatric-onset movement disorders with unrevealing etiologies. Whole exome sequencing was performed and rare variants were interrogated for pathogenicity. Genetic diagnoses have been confirmed in 10 patients with disease-causing variants in CTNNB1, SPAST, ATP1A3, PURA, SLC2A1, KMT2B, ACTB, GNAO1 and SPG11. 80% (8/10) of patients with genetic diagnosis have potential treatment implications and treatments have been offered to them. One patient with KMT2B dystonia showed clinical improvement with decrease in dystonia after receiving globus pallidus interna deep brain stimulation. Conclusions A diagnostic yield of 32% (10/31) was reported in our cohort and this allows a better prediction of prognosis and contributes to a more effective clinical management. The study highlights the potential of implementing precision medicine in the patients.

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Novel MYO15A variants are associated with hearing loss in the two Iranian pedigrees

BMC Medical Genetics ◽

10.1186/s12881-020-01168-x ◽

2020 ◽

Vol 21 (1) ◽

Author(s):

Somayeh Khatami ◽

Masomeh Askari ◽

Fatemeh Bahreini ◽

Morteza Hashemzadeh-Chaleshtori ◽

Saeed Hematian ◽

...

Keyword(s):

Hearing Loss ◽

Exome Sequencing ◽

Whole Exome Sequencing ◽

Genetic Diagnosis ◽

Clinical Genetic ◽

Large Size ◽

Whole Exome ◽

Novel Variants ◽

Syndromic Hearing Loss ◽

Traditional Approaches

Abstract Background Clinical genetic diagnosis of non-syndromic hearing loss (NSHL) is quite challenging. With regard to its high heterogeneity as well as large size of some genes, it is also really difficult to detect causative mutations using traditional approaches. One of the recent technologies called whole-exome sequencing (WES) has been thus developed in this domain to remove the limitations of conventional methods. Methods This study was a report on a research study of two unrelated pedigrees with multiple affected cases of hearing loss (HL). Accordingly, clinical evaluations and genetic analysis were performed in both families. Results The results of WES data analysis to uncover autosomal recessive non-syndromic hearing loss (ARNSHL) disease-causing variants was reported in the present study. Initial analysis identified two novel variants of MYO15A i.e. c.T6442A:p.W2148R and c.10504dupT:p.C3502Lfs*15 correspondingly which were later confirmed by Sanger validations and segregation analyses. According to online prediction tools, both identified variants seemed to have damaging effects. Conclusion In this study, whole exome sequencing were used as a first approach strategy to identify the two novel variants in MYO15A in two Iranian families with ARNSHL.

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Genetic Diagnosis Using Whole Exome Sequencing in Common Variable Immunodeficiency

Frontiers in Immunology ◽

10.3389/fimmu.2016.00220 ◽

2016 ◽

Vol 7 ◽

Cited By ~ 117

Author(s):

Patrick Maffucci ◽

Charles A. Filion ◽

Bertrand Boisson ◽

Yuval Itan ◽

Lei Shang ◽

...

Keyword(s):

Exome Sequencing ◽

Whole Exome Sequencing ◽

Common Variable Immunodeficiency ◽

Genetic Diagnosis ◽

Whole Exome ◽

Common Variable

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Identification of Two Novel Mutations in PKHD1 Gene from Two Families with Polycystic Kidney Disease by Whole Exome Sequencing

Current Genomics ◽

10.2174/1389202922666210219111810 ◽

2021 ◽

Vol 22 ◽

Author(s):

Masoud Heidari ◽

Hamid Gharshasbi ◽

Alireza Isazadeh ◽

Morteza Soleyman-Nejad ◽

Mohammad Hossein Taskhiri ◽

...

Keyword(s):

Kidney Disease ◽

Exome Sequencing ◽

Polycystic Kidney Disease ◽

Whole Exome Sequencing ◽

Novel Mutation ◽

Genetic Diagnosis ◽

Genetic Alterations ◽

Polycystic Kidney ◽

Novel Mutations ◽

Whole Exome

Background:: Polycystic kidney disease (PKD) is an autosomal recessive disorder resulting from mutations in the PKHD1 gene on chromosome 6 (6p12), a large gene spanning 470 kb of genomic DNA. Objective: The aim of the present study was to report newly identified mutations in the PKHD1 gene in two Iranian families with PKD. Materials and Methods: Genetic alterations of a 3-month-old boy and a 27-year-old girl with PKD were evaluated using whole-exome sequencing. The PCR direct sequencing was performed to analyse the co-segregation of the variants with the disease in the family. Finally, the molecular function of the identified novel mutations was evaluated by in silico study. Results: In the 3 month-old boy, a novel homozygous frameshift mutation was detected in the PKHD1 gene, which can cause PKD. Moreover, we identified three novel heterozygous missense mutations in ATIC, VPS13B, and TP53RK genes. In the 27-year-old woman, with two recurrent abortions history and two infant mortalities at early weeks due to metabolic and/or renal disease, we detected a novel missense mutation on PKHD1 gene and a novel mutation in ETFDH gene. Conclusion: In general, we have identified two novel mutations in the PKHD1 gene. These molecular findings can help accurately correlate genotype and phenotype in families with such disease in order to reduce patient births through preoperative genetic diagnosis or better management of disorders.

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Screening of Candidate Pathogenic Genes for Spontaneous Abortion using Whole Exome Sequencing

Combinatorial Chemistry & High Throughput Screening ◽

10.2174/1386207324666210628115715 ◽

2021 ◽

Vol 24 ◽

Author(s):

Qingwen Zhu ◽

Yiwen Zhou ◽

Jiayi Ding ◽

Li Chen ◽

Jia Liu ◽

...

Keyword(s):

Exome Sequencing ◽

Whole Exome Sequencing ◽

Spontaneous Abortion ◽

Gene Fusion ◽

High Throughput Sequencing ◽

Kegg Pathway ◽

Novel Mutation ◽

Common Disease ◽

Pathogenic Genes ◽

Whole Exome

Background: Spontaneous abortion is a common disease in obstetrics and reproduction. Objective: This study aimed to screen candidate pathogenic genes for spontaneous abortion using whole-exome sequencing. Methods: Genomic DNA was extracted from abortion tissues of spontaneous abortion patients and sequenced using the Illumina HiSeq2500 high-throughput sequencing platform. Whole exome sequencing was performed to select harmful mutations, including SNP and insertion and deletion sites, associated with spontaneous abortion. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses and gene fusion analyses were performed. MUC3A and PDE4DIP were two novel mutation genes that were screened and verified by PCR in abortion tissues of patients. Results: A total of 83,633 SNPs and 13,635 Indel mutations were detected, of which 29172 SNPs and 3093 Indels were screened as harmful mutations. The 7 GO-BP, 4 GO-CC, 9 GO-MF progress, and 3 KEGG pathways were enriched in GO and KEGG pathway analyses. A total of 746 gene fusion mutations were obtained, involving 492 genes. MUC3A and PDE4DIP were used for PCR verification because of their high number of mutation sites in all samples. Conclusion: There are extensive SNPs and Indel mutations in the genome of spontaneous abortion tissues, and the effect of these gene mutations on spontaneous abortion needs further experimental verification.

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RHOBTB2 p.Arg511Trp Mutation in Early Infantile Epileptic Encephalopathy-64: Review and Case Report

Journal of Pediatric Genetics ◽

10.1055/s-0040-1722288 ◽

2021 ◽

Author(s):

J Fonseca ◽

C Melo ◽

C Ferreira ◽

M Sampaio ◽

R Sousa ◽

...

Keyword(s):

Case Report ◽

Intellectual Disability ◽

Status Epilepticus ◽

Exome Sequencing ◽

Whole Exome Sequencing ◽

Epileptic Encephalopathy ◽

Btb Domain ◽

Pathogenic Variants ◽

Severe Intellectual Disability ◽

Whole Exome

AbstractEarly infantile epileptic encephalopathy-64 (EIEE 64), also called RHOBTB2-related developmental and epileptic encephalopathy (DEE), is caused by heterozygous pathogenic variants (EIEE 64; MIM#618004) in the Rho-related BTB domain-containing protein 2 (RHOBTB2) gene. To date, only 13 cases with RHOBTB2-related DEE have been reported. We add to the literature the 14th case of EIEE 64, identified by whole exome sequencing, caused by a heterozygous pathogenic variant in RHOBTB2 (c.1531C > T), p.Arg511Trp. This additional case supports the main features of RHOBTB2-related DEE: infantile-onset seizures, severe intellectual disability, impaired motor functions, postnatal microcephaly, recurrent status epilepticus, and hemiparesis after seizures.

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