[McArdle's disease in adults: clinical and genetic study].

McArdle's disease is a rare metabolic myopathy resulting from an absence of functional muscle glycogen phosphorylase that is inherited as an autosomal recessive condition. Recent molecular genetic studies have identified more than ten different mutations in patients with McArdle's disease, although a nonsense point mutation at codon 49 in exon 1 (R49X) accounts for approximately 85% of mutant alleles in American and British patients. We describe clinical, biochemical and genetic characteristics of five adults patients with McArdle's disease studied at our hospital during the last 10 years.