Late-onset acid maltase deficiency in a Chinese girl.

Late-onset acid maltase deficiency is a rare disorder. We describe a nineteen year old Chinese girl who presented with diarrhoea, limb-girdle weakness and respiratory failure requiring mechanical ventilation. Electromyography showed polyphasic potentials and myotonic discharges. Muscle biopsy revealed features characteristic of acid maltase deficiency. Assay of acid alpha-glucosidase in cultured skin fibroblasts confirmed the diagnosis. Supportive treatment with nocturnal intermittent positive pressure ventilation via a nasal mask and dietary supplementation with branched-chain aminoacids proved effective in this patient. The cause of diarrhoea remained uncertain. This is the first documented case of acid maltase deficiency in Chinese adult.