Whole Exome Sequencing Reveals DYSF, FKTN, and ISPD Mutations in Congenital Muscular Dystrophy Without Brain or Eye Involvement

Introduction. Hereditary motor and sensory neuropathies, a highly genetic heterogeneous group of disorders, have a phenotype caused by peripheral nerve damage.Purpose of the study – to assess the extent of genetic heterogeneity of hereditary motor and sensory neuropathies in Russian patients and to evaluate the diagnostic effectiveness of using full-exome research methods to find the genetic cause of hereditary motor and sensory neuropathies.Materials and methods. The material for the study was DNA samples from 51 patients and their family members referred for whole exome sequencing to the DNA-diagnostics laboratory of Research Centre for Medical Genetics in 2017–2019. Methods: whole exome sequencing, Sanger sequencing, restriction fragment length polymorphism.Results. Whole exome sequencing in combination with segregation analysis of the pathogenic variants in families allowed to determine the cause of the disease in 41 % of cases. In another 16 % of cases, candidate genetic variants as a possible cause of the disease were revealed, but additional studies are needed to confirm it. The most frequently mutated gene was MFN2 caused neuropathy in 6 unrelated families. MPZ gene mutations were detected in two families, AARS gene mutations were revealed in another two families, and mutations in GJB1, HINT1, INF2, LRSAM1, LITAF, MME, NEFL, WWOX were detected once. Among the causal variants, mutations in B4GALNT1 caused spastic paraplegia, in COL6A1 led to Bethlem’s congenital muscular dystrophy, and in SYT2 caused congenital myasthenic syndrome indicating difficulties in differential diagnosis of inherited neuromuscular disorders. A PMP22 duplication was detected in 2 families prior to whole exome sequencing.Conclusion. Whole exome sequencing is very important for finding the molecular cause of hereditary motor and sensory neuropathies. In most cases, additional methods should be used to clarify the pathogenicity of variants detected by whole exome sequencing. However, it is necessary to remember that the most common cause of the disease is a large duplication of the region 17p11.2.

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Homozygous missense variant in the TTN gene causing autosomal recessive limb-girdle muscular dystrophy type 10

BMC Medical Genetics ◽

10.1186/s12881-019-0895-7 ◽

2019 ◽

Vol 20 (1) ◽

Cited By ~ 5

Author(s):

Amjad Khan ◽

Rongrong Wang ◽

Shirui Han ◽

Muhammad Umair ◽

Safdar Abbas ◽

...

Keyword(s):

Muscular Dystrophy ◽

Exome Sequencing ◽

Whole Exome Sequencing ◽

Autosomal Recessive ◽

Missense Variant ◽

Pathogenic Variant ◽

Limb Girdle Muscular Dystrophy ◽

Molecular Diagnostic ◽

Sequencing Analysis ◽

Whole Exome

Abstract Background Limb-girdle muscular dystrophies (LGMDs) are large group of heterogeneous genetic diseases, having a hallmark feature of muscle weakness. Pathogenic mutations in the gene encoding the giant skeletal muscle protein titin (TTN) are associated with several muscle disorders, including cardiomyopathy, recessive congenital myopathies and limb-girdle muscular dystrophy (LGMD) type10. The phenotypic spectrum of titinopathies is expanding, as next generation sequencing (NGS) technology makes screening of this large gene possible. Aim This study aimed to identify the pathogenic variant in a consanguineous Pakistani family with autosomal recessive LGMD type 10. Methods DNA from peripheral blood samples were obtained, whole exome sequencing (WES) was performed and several molecular and bioinformatics analysis were conducted to identify the pathogenic variant. TTN coding and near coding regions were further amplified using PCR and sequenced via Sanger sequencing. Results Whole exome sequencing analysis revealed a novel homozygous missense variant (c.98807G > A; p.Arg32936His) in the TTN gene in the index patients. No heterozygous individuals in the family presented LGMD features. The variant p.Arg32936His leads to a substitution of the arginine amino acid at position 32,936 into histidine possibly causing LGMD type 10. Conclusion We identified a homozygous missense variant in TTN, which likely explains LGMD type 10 in this family in line with similar previously reported data. Our study concludes that WES is a successful molecular diagnostic tool to identify pathogenic variants in large genes such as TTN in highly inbred population.

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Whole-Exome Sequencing Identifies Small Mutations in Pakistani Muscular Dystrophy Patients

Genetic Testing and Molecular Biomarkers ◽

10.1089/gtmb.2020.0246 ◽

2021 ◽

Vol 25 (3) ◽

pp. 218-226

Author(s):

Mehwish Zehravi ◽

Mohsin Wahid ◽

Junaid Ashraf ◽

Tehseen Fatima

Keyword(s):

Muscular Dystrophy ◽

Exome Sequencing ◽

Whole Exome Sequencing ◽

Whole Exome

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Whole Exome Sequencing Aids The Diagnosis of Fetal Skeletal Dysplasia

10.21203/rs.3.rs-46976/v1 ◽

2020 ◽

Author(s):

Hui Tang ◽

Qin Zhang ◽

Linliang Yin ◽

Jingjing Xiang ◽

Jing Wang ◽

...

Keyword(s):

Muscular Dystrophy ◽

Exome Sequencing ◽

Whole Exome Sequencing ◽

Skeletal Dysplasia ◽

Clinical Symptoms ◽

Single Nucleotide Polymorphism Array ◽

Snp Array ◽

Somatic Mosaicism ◽

Single Nucleotide ◽

Whole Exome

Abstract Background: Skeletal dysplasia is a complex group of bone and cartilage disorders with strong clinical and genetical heterogeneousity. Several types have prenatal phenotypes. And it is difficult to make a molecular diagnosis rapidly due to lacking family history and non-specific and limited clinical symptoms in utero. This study aims to diagnose 16 Chinese fetuses with skeletal dysplasia.Methods: Single nucleotide polymorphism-array (SNP-array) was performed in 12 of 16 samples. If no microdeletions or microreplications related to skeletal dysplasia were detected, whole-exome sequencing (WES) was adopted. And the last four cases only got whole-exome sequencing for analyzing copy number variants and single nucleotide variations at the same time.Results: Among the 16 cases, 12 patients received definitive diagnosis and we detected one deletion in DMD gene by SNP-array and 15 variants of 6 genes including FGFR3, COL1A1, COL1A2, ALPL, HSPG2 and DYNC2H1. 8 variants of COL1A1, COL1A2, ALPL and HSPG2 are novel. And somatic mosaicism in asymptomatic parent with mutations in COL1A1 or COL1A2 was observed.Conclusions: In general, our study expanded the prenatal phenotypes in Duchenne muscular dystrophy (DMD)/ Becker muscular dystrophy (BMD), found 8 novel variants and elucidated that the utilization of whole-exome sequencing improved the diagnosis yield of skeletal dysplasia and provided useful genetic counseling guidance for parents.

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Case Report: Whole-Exome Sequencing With MLPA Revealed Variants in Two Genes in a Patient With Combined Manifestations of Spinal Muscular Atrophy and Duchenne Muscular Dystrophy

Frontiers in Genetics ◽

10.3389/fgene.2021.605611 ◽

2021 ◽

Vol 12 ◽

Author(s):

Yu Xia ◽

Yijie Feng ◽

Lu Xu ◽

Xiaoyang Chen ◽

Feng Gao ◽

...

Keyword(s):

Duchenne Muscular Dystrophy ◽

Muscular Dystrophy ◽

Spinal Muscular Atrophy ◽

Exome Sequencing ◽

Whole Exome Sequencing ◽

Muscular Atrophy ◽

Genetic Disorder ◽

Clinical Manifestations ◽

Chinese Family ◽

Whole Exome

Spinal muscular atrophy (SMA) and Duchenne muscular dystrophy (DMD) are two common kinds of neuromuscular disorders sharing various similarities in clinical manifestations. SMA is an autosomal recessive genetic disorder that results from biallelic mutations of the survival motor neuron 1 gene (SMN1; OMIM 600354) on the 5q13 chromosome. DMD is an X-linked disorder caused by defects in the DMD gene (OMIM 300377) on the X chromosome. Here, for the first time, we report a case from a Chinese family who present with clinical manifestations of both two diseases, including poor motor development and progressive muscle weakness. We identified a homozygous deletion in exons 7 and 8 of the SMN1 gene and a deletion in exon 50 of the DMD gene by whole-exome sequencing (WES) and multiplex ligation-dependent probe amplification (MLPA). This case expands our understanding of diagnosis for synchronous SMA and DMD and highlights the importance of various genetic testing methods, including WES, in differential diagnosis of neuromuscular diseases.

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