ICNC Abstracts, ICNC 2018

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Collagen VI related myopathies: clinical variability of triple-helical domain mutations of COL6A mutations
Sophelia HS Chan, Ka Yee Anna Kwong, Ho Ming Luk, Fai Man Ivan Lo, Tsui Hang Sharon Fung, Ho Yin Mandy Tsang, Ho Yin Brian Chung, On-Kei Angel Chan

Last modified: 2018-09-09

Abstract


Background and Purpose: Mutations in collagen VI-related genes (COL6A1, COL6A2, andCOL6A3) cause Ullrich congenital muscular dystrophy (UCMD) the severe disease, the mild Bethlem myopathy (BM) and the intermediate  phenotype. These were not separate entities but represent a continuous clinical spectrum. We aimed to analyze the clinical, pathologic, and genetic characteristics of patients with collagen VI-related myopathy in Hong Kong.

Methods: We reviewed the clinical, pathologic, radiological and genetic features in 8 patients with collagenVI-related myopathy from 8 families, with confirmed mutations of collagen VI-related genes.

Results: One patient showed the phenotype of typical UCMD, 3 patients had the intermediate collagen VI-related myopathies (IM), and 4 patients had the BM phenotype. Based on genetic analysis, all patients had mutation in the triple-helical domain of the COL6A related genes. The mutations affected either in COL6A1, COL6A2, COL6A3 gene and include 8 point mutations, one inframe deletion and one splice site insertion. Dominant negative mutations occur in 6 patients and recessive mutations mainly in 2 patients with BM phenotype. Additionally, we found two novel mutations: NM_001849.3: c.1084_1092del, p.(Ser362_Gly364del)] and NM_001849.3: c.811G>C, p.(Gly271Arg) in COL6A2

Conclusions: Missense mutations in the triple-helical domain of the three major collagen VI genes are the most common mutations related to collagen VI-related myopathy in Hong Kong. Mutations in the triple-helical domain of our patients give rise to a broad clinical spectrum from the mild end to the severe phenotype.


Keywords


collagen VI related myopathies; muscular dystrophy, COL6A1,COL6A2, COL6A3

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