Neurogenetics, 2014, 01, 171─182

Recessive C10orf2 mutations in a family with infantile-onset spinocerebellar ataxia, sensorimotor polyneuropathy, and myopathy

Mi-Hyun Park, Hae-Mi Woo , Young Bin Hong , Ji Hoon Park , Bo Ram Yoon , Jin-Mo Park , Jeong Hyun Yoo , Heasoo Koo , Jong-Hee Chae , Ki Wha Chung , Byung-Ok Choi , Soo Kyung Koo

Abstract

Recessive mutations in chromosome 10 open reading frame 2 (C10orf2) are relevant in infantile-onset spinocerebellar ataxia (IOSCA). In this study, we investigated the causative mutation in a Korean family with combined phenotypes of IOSCA, sensorimotor polyneuropathy, and myopathy. We investigated recessive mutations in a Korean family with two individuals affected by IOSCA. Causative mutations were investigated using whole exome sequencing. Electrophysiological analyses and muscle and nerve biopsies were performed, along with magnetic resonance imaging (MRI) of the brain and lower extremities. Compound heterozygous mutations c.1460C>T and c.1485-1G>A in C10orf2 were identified as causative of IOSCA. Skeletal muscle showed mitochondrial DNA (mtDNA) deletions. Both patients showed a period of normal development until 12？ 15 months, followed by ataxia, athetosis, hearing loss, and intellectual disability. Electrophysiological findings indicated motor and sensory polyneuropathies. Muscle biopsy revealed variations in the size and shape of myofibers with scattered, small, and angulated degenerating myofibers containing abnormal mitochondria; these observations are consistent with myopathy and may be the result of mtDNA deletions. Sural nerve biopsy revealed an axonal neuropathy. High-signalintensity lesions in the middle cerebellar peduncles were correlated with clinical severity, and MRI of the lower legs was compatible with the hypothesis of length-dependent axonal degeneration. We identified novel compound heterozygous mutations of the C10orf2 gene as the cause of IOSCA with sensorimotor polyneuropathy and myopathy. Signs of motor neuropathy and myopathy were discovered for the first time in IOSCA patients with C10orf2 mutations. These results suggest that the clinical spectrum of IOSCA caused by C10orf2 mutations may be more variable than previously reported.

• ISBN or ISSN: 1364-6745

• 본 연구는 질병관리본부 연구개발과제(과제번호 2012-NG61004-00) 연구비를 지원받아 수행되었습니다.
• This research was supported by a fund(code 2012-NG61004-00) by Research of Korea Centers for Disease Control and Prevention.