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Identification of two novel insertion abnormal transcripts in two Chinese families affected with Dystrophinopathy.

ABSTRACT: BACKGROUND:Duchenne muscular dystrophy (DMD) is an X-linked recessive inheritance muscle dystrophy disease, associated with pathogenic variants in the DMD gene. MLPA, DHPLC and DMD sequence studies fail to found the causative alteration in two cases. This study intends to evaluate the disease-causing mutations and explains the correlation genotype-phenotype. METHODS:The mRNA analysis and Long-range PCR with sequencing were used for molecular diagnosis. RESULTS:In case one, an insertion of 78 nucleotides between exons 40 and 41 (r.5739_5740insMN602429:r415_492) was identified in case one. The insertion sequences were highly homologous to the intron 40 (NG_012232.1:g.1001760_g.1001837). Long-range PCR with sequencing analysis showed that a novel deep intronic DMD mutation (NG_012232.1:g.1001838A>G) was identified, generating a premature stop codon and terminating protein translation. The likely pathogenic mutation was detected in fetal sample. In case two, an insertion of 74 nucleotides which located inside the consensus sequence AG/GT was detected between exons 2 and 3 (r.93_94insMN584887:r61_134), which resulted in a premature stop codon. The insertion sequences were traceable in the intron 2 of DMD gene (NG_012232.1:g.415926_g.415999). We did not perform prenatal DMD gene diagnosis for case two due to lack of sufficient genetic information. CONCLUSION:These findings clarify importance of proceeding to the mRNA analysis when no causative mutations were found neither by MLPA/DHPLC nor gene sequencing so as to reach the molecular confirmation of DMD and carry out an accurate genetic assessment/ carrier status testing.

SUBMITTER: Xu Y

PROVIDER: S-EPMC7171295 | biostudies-literature | 2020 Apr

REPOSITORIES: biostudies-literature

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Identification of two novel insertion abnormal transcripts in two Chinese families affected with Dystrophinopathy.

Xu Ying Y Song Tingting T Li Yu Y Guo Fenfen F Jin Xin X Cheng Lu L Zheng Jiao J Li Chunyan C Zhang Yingqi Y Chen Biliang B Zhang Jianfang J

Journal of clinical laboratory analysis 20191203 4

<h4>Background</h4>Duchenne muscular dystrophy (DMD) is an X-linked recessive inheritance muscle dystrophy disease, associated with pathogenic variants in the DMD gene. MLPA, DHPLC and DMD sequence studies fail to found the causative alteration in two cases. This study intends to evaluate the disease-causing mutations and explains the correlation genotype-phenotype.<h4>Methods</h4>The mRNA analysis and Long-range PCR with sequencing were used for molecular diagnosis.<h4>Results</h4>In case one, ...[more]

PMID: 31793735

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Project description:ObjectiveTo identify the causative mutations in two Chinese families with retinitis pigmentosa (RP), and to describe the associated phenotype.MethodsIndividuals from two unrelated families underwent full ophthalmic examinations. After informed consent was obtained, genomic DNA was extracted from the venous blood of all participants. Linkage analysis was performed on the known genetic loci for autosomal dominant retinitis pigmentosa with a panel of polymorphic markers in the two families, and then all coding exons of the PRP31 premessenger ribonucleic acid processing factor 31 homolog (PRPF31) gene were screened for mutations with direct sequencing of PCR-amplified DNA fragments. Allele-specific PCR was used to validate a substitution in all available family members and 100 normal controls. A large deletion was detected with real-time quantitative PCR (RQ-PCR) using a panel of primers from regions around the PRPF31 gene. Long-range PCR, followed by DNA sequencing, was used to define the breakpoints.ResultsClinical examination and pedigree analysis revealed two four-generation families (RP24 and RP106) with autosomal dominant retinitis pigmentosa. A significant two-point linkage odd disequilibrium score was generated at marker D19S926 (Zmax=3.55, θ=0) for family RP24 and D19S571 (Zmax=3.21, θ=0) for family RP106, and further linkage and haplotype studies confined the disease locus to chromosome 19q13.42 where the PRPF31 gene is located. Mutation screening of the PRPF31 gene revealed a novel deletion c.1215delG (p.G405fs+7X) in family RP106. The deletion cosegregated with the family's disease phenotype, but was not found in 100 normal controls. No disease-causing mutation was detected in family RP24 with PCR-based sequencing analysis. RQ-PCR and long-range PCR analysis revealed a complex insertion-deletion (indel) in the patients of family RP24. The deletion is more than 19 kb and encompasses part of the PRPF31 gene (exons 1-3), together with three adjacent genes.ConclusionsOur results further confirmed that haploinsufficiency is the main mechanism for RP11 and that genomic arrangements may be prevalent in PRPF31 mutations.

Dataset Information

Identification of two novel insertion abnormal transcripts in two Chinese families affected with Dystrophinopathy.

Publications

Identification of two novel insertion abnormal transcripts in two Chinese families affected with Dystrophinopathy.

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