Fukutin gene retrotransposal insertion in a non-Japanese Fukuyama congenital muscular dystrophy (FCMD) patient

Fukuyama-type congenital muscular dystrophy (FCMD) is an autosomal recessive disorder, characterized by severe muscular dystrophy associated with brain malformation. FCMD is the second most common form of muscular dystrophy and one of the most common autosomal recessive diseases among the Japanese population; however, no typical FCMD cases have been reported in any other population. In this study, we report on the first identification of a Chinese FCMD patient; our findings are supported by clinical, histological, and magnetic resonance imaging (MRI) evidence, as well as fukutin gene mutational analyses. The patient presented with neonatal hypotonia, seizures, and delayed motor and speech development. Additional testing revealed cerebral and cerebellar gyrus abnormalities with white matter signal intensity changes, elevated serum creatine kinase (CK) levels, and dystrophic skeletal muscle with alpha-dystroglycan hypoglycosylation, and normal beta-dystroglycan and merosin expression. Genetic analysis of the fukutin gene showed one copy with a Japanese founder 3-kilobase (kb) retrotransposal insertion in the 3'-non-coding region and the other copy with a known c.139C>T mutation. This is the first FCMD case reported in the Chinese population and the first case in which the 3-kb insertion has been found outside of the Japanese population. This report emphasizes the importance of considering the fukutin founder mutation for diagnostic purposes outside of Japan.