Identification of two rare mutations c.1318G>A and c.6438+2T>G in a Chinese DMD family as genetic markers

다국어 초록 (Multilingual Abstract)

Background Duchenne muscular dystrophy (DMD) is a fatal X-linked recessive disorder with no efective treatment, which underscores the importance of avoiding the birth of children with DMD by identifying pathogenic mutations and obtaining an accurate prenatal diagnosis. Objective The objective of this study was to analyze the genetic defect of a Chinese family where all male patients have died of DMD. Methods Multiplex ligation dependent probe analysis (MLPA) and next-generation sequencing (NGS) were employed to detect DMD mutations. The candidate mutations were then validated by Sanger sequencing. In vitro splicing assay was further conducted to examine the potential efect of the novel DMD splice site mutation on splicing. Results We found that two rare DMD mutations c.1318G>A and c.6438+2T>G passed from generation to generation among female carriers and they may be used as genetic markers in the Chinese DMD family. In vitro splicing assay further revealed that the novel classical splice site mutation c.6438+2T>G gave rise to a new donor splice site, which resulted in a frame shift of the transcripts and a premature termination at position 2159 in exon 45 (p.Y2144Nfs*16). Conclusion We found that two co-inherited mutations passed from generation to generation in female carriers and they may be used as genetic markers in the Chinese DMD family. Our fndings not only expanded the DMD mutation spectrum, but also provided an important basis for identifying of female carriers and avoiding the birth of afected male children in this DMD family.

참고문헌 (Reference)

1 Cooper TA, "The regulation of splice-site selection, and its role in human disease" 61 : 259-266, 1997

2 Koenig M, "The molecular basis for Duchenne versus Becker muscular dystrophy : correlation of severity with type of deletion" 45 : 498-506, 1989

3 Richards S, "Standards and guidelines for the interpretation of sequence variants : a joint consensus recommendation of the American College of Medical Genetics and Genomics and the Association for Molecular Pathology" 17 : 405-424, 2015

4 Tuffery-Giraud S, "Point mutations in the dystrophin gene: evidence for frequent use of cryptic splice sites as a result of splicing defects" 14 : 359-368, 1999

5 Ebrahimzadeh-Vesal R, "Next Generation Sequencing approach to molecular diagnosis of Duchenne muscular dystrophy; identification of a novel mutation" 644 : 1-3, 2018

6 Takeshima Y, "Mutation spectrum of the dystrophin gene in 442 Duchenne/Becker muscular dystrophy cases from one Japanese referral center" 55 : 379-388, 2010

7 Elhawary NA, "Molecular characterization of exonic rearrangements and frame shifts in the dystrophin gene in Duchenne muscular dystrophy patients in a Saudi community" 12 : 18-, 2018

8 Juan-Mateu J, "Interplay between DMD point mutations and splicing signals in Dystrophinopathy phenotypes" 8 : e59916-, 2013

9 Habara Y, "In vitro splicing analysis showed that availability of a cryptic splice site is not a determinant for alternative splicing patterns caused by + 1G–>A mutations in introns of the dystrophin gene" 46 : 542-547, 2009

10 Wu B, "Identification of a novel DMD duplication identified by a combination of MLPA and targeted exome sequencing" 10 : 8-, 2017

11 Aartsma-Rus A, "Entries in the Leiden Duchenne muscular dystrophy mutation database : an overview of mutation types and paradoxical cases that confirm the reading-frame rule" 34 : 135-144, 2006

12 Lai Y, "Dystrophins carrying spectrin-like repeats 16 and 17 anchor nNOS to the sarcolemma and enhance exercise performance in a mouse model of muscular dystrophy" 119 : 624-635, 2009

13 Yiu EM, "Duchenne muscular dystrophy" 51 : 759-764, 2015

14 Bushby K, "Diagnosis and management of Duchenne muscular dystrophy, part 1 : diagnosis, and pharmacological and psychosocial management" 9 : 77-93, 2010

15 Li F, "Detection of pathogenic mutations and the mechanism of a rare chromosomal rearrangement in a Chinese family with Becker muscular dystrophy" 414 : 20-25, 2012

16 Lalic T, "Deletion and duplication screening in the DMD gene using MLPA" 13 : 1231-1234, 2005

17 White S, "Comprehensive detection of genomic duplications and deletions in the DMD gene, by use of multiplex amplifiable probe hybridization" 71 : 365-374, 2002

18 Koenig M, "Complete cloning of the Duchenne muscular dystrophy(DMD)cDNA and preliminary genomic organization of the DMD gene in normal and affected individuals" 50 : 509-517, 1987

19 Monaco AP, "An explanation for the phenotypic differences between patients bearing partial deletions of the DMD locus" 2 : 90-95, 1988

20 Zimowski JG, "A rare subclinical or mild type of Becker muscular dystrophy caused by a single exon 48 deletion of the dystrophin gene" 58 : 343-347, 2017

21 Tang J, "A novel DMD splicing mutation found in a family responsible for X-linked dilated cardiomyopathy with hyper-CKemia" 97 : e11074-, 2018

22 Rybakova IN, "A new model for the interaction of dystrophin with F-actin" 135 : 661-672, 1996

23 Yu H, "A De novo Mutation in Dystrophin Causing Muscular Dystrophy in a Female Patient" 130 : 2273-2278, 2017