Exome sequencing identifies a novel SMCHD1 mutation in facioscapulohumeral muscular dystrophy 2
Department of Cell and Developmental Biology
Medical Subject Headings
Adolescent; Chromosomal Proteins, Non-Histone; Cytokines; DNA Mutational Analysis; Exome; Family Health; Humans; Male; Muscular Dystrophy, Facioscapulohumeral; Phenotype
Cell Biology | Developmental Biology | Molecular Biology | Molecular Genetics | Musculoskeletal Diseases | Nervous System Diseases
FSHD2 is a rare form of facioscapulohumeral muscular dystrophy (FSHD) characterized by the absence of a contraction in the D4Z4 macrosatellite repeat region on chromosome 4q35 that is the hallmark of FSHD1. However, hypomethylation of this region is common to both subtypes. Recently, mutations in SMCHD1 combined with a permissive 4q35 allele were reported to cause FSHD2. We identified a novel p.Lys275del SMCHD1 mutation in a family affected with FSHD2 using whole-exome sequencing and linkage analysis. This mutation alters a highly conserved amino acid in the ATPase domain of SMCHD1. Subject III-11 is a male who developed asymmetrical muscle weakness characteristic of FSHD at 13 years. Physical examination revealed marked bilateral atrophy at biceps brachii, bilateral scapular winging, some asymmetrical weakness at tibialis anterior and peroneal muscles, and mild lower facial weakness. Biopsy of biceps brachii in subject II-5, the father of III-11, demonstrated lobulated fibers and dystrophic changes. Endomysial and perivascular inflammation was found, which has been reported in FSHD1 but not FSHD2. Given the previous report of SMCHD1 mutations in FSHD2 and the clinical presentations consistent with the FSHD phenotype, we conclude that the SMCHD1 mutation is the likely cause of the disease in this family.
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Citation: Mitsuhashi S, Boyden SE, Estrella EA, Jones TI, Rahimov F, Yu TW, Darras BT, Amato AA, Folkerth RD, Jones PL, Kunkel LM, Kang PB. Exome sequencing identifies a novel SMCHD1 mutation in facioscapulohumeral muscular dystrophy 2. Neuromuscul Disord. 2013 Dec;23(12):975-80. doi: 10.1016/j.nmd.2013.08.009. Epub 2013 Aug 31. PubMed PMID: 24128691; PubMed Central PMCID: PMC3851942. Link to article on publisher's site
Mitsuhashi, Satomi; Boyden, Steven E.; Estrella, Elicia A.; Jones, Takako I.; Rahimov, Fedik; Yu, Timothy W.; Darras, Basil T.; Amato, Anthony A.; Folkerth, Rebecca D.; Jones, Peter L.; Kunkel, Louis M.; and Kang, Peter B., "Exome sequencing identifies a novel SMCHD1 mutation in facioscapulohumeral muscular dystrophy 2" (2013). Peter Jones Lab Publications. 30.