Prevalence of neuromuscular diseases in Chinese children: a study in southern China.

Our objective was to study the prevalence of neuromuscular diseases in Chinese children. A prospective study of neuromuscular diseases in Chinese children was conducted from 1985 to 2001 in Hong Kong, which is a city in southern China. The population census of June 30, 2001, was used to calculate the prevalence of neuromuscular diseases in Chinese children. Altogether, 332 children aged < 19 years at first assessment with neuromuscular diseases confirmed by using electromyography, muscle biopsy, and/or molecular genetic study were included in the study. Of these, 228 (68%) had inherited and 104 (32%) had noninherited neuromuscular diseases. Of the inherited neuromuscular diseases, the most common were the dystrophinopathies, including Duchenne muscular dystrophy (n = 66) and Becker muscular dystrophy (n = 8). Spinal muscular atrophy was the second most common (n = 61). Of the noninherited neuromuscular disorders, myasthenia gravis was the most common (n = 62, 60%). Nearly 88% of the cases of myasthenia gravis were ocular type. The prevalence rate of neuromuscular diseases in June 2001 (n = 291 surviving) is estimated to be 214 x 10(-6). The estimated prevalence rate of neuromuscular diseases in our Chinese children is 1 in 4669.