S. Tsujino et al., 3 NEW MUTATIONS IN PATIENTS WITH MYOPHOSPHORYLASE DEFICIENCY (MCARDLEDISEASE), American journal of human genetics, 54(1), 1994, pp. 44-52
We report three new mutations in patients with myophosphorylase defici
ency (McArdle disease). A splice-junction mutation (G-to-A transition
at the 5' end of intron 14) and a missense mutation (CTG to CCG at cod
on 291, changing an encoded leucine to a proline) were identified in C
aucasian patients who were heterozygous for a common mutation reported
elsewhere (CGA [Arg] to TGA [stop]) at codon 49. The splice-junction
mutation destroyed the consensus sequence at the 5' splice site, and a
cryptic splice site 67 bp upstream was recognized instead. As a resul
t, there was a 67-bp deletion in the 3'-terminal region of exon 14 in
the transcript, resulting in a frameshift with premature translation t
ermination. A deletion of a single codon, 708/709 (TTC, specifying phe
nylalanine) was identified in Japanese patients. Two affected siblings
were homozygotes, and their parents were heterozygotes. A third, unre
lated patient was heterozygous for the same mutation, while the myopho
sphorylase gene on the other allele was only faintly expressed.