Phenotypic variability in a Spanish family with a Caveolin-3 mutation

We report a Spanish family affected from a late onset, hand-involved and autosomal dominant distal myopathy associated to Caveolin-3 mutation. Signs of muscle hyperexcitability and hyperckemia were observed in the youngest relatives but not motor symptoms.

Neurological examination was performed in all members of the family. Muscle biopsy sample was taken from the proband and DNA genomics was amplified for the two exons of Cav-3 by the polymerase chain reaction (PCR) in all the affected members and in three asymptomatic relatives.

Signs of muscle hyperexcitability and hyperckemia were observed in the affected members from early ages. Cav-3 expression was greatly reduced in the sarcolemma of the proband's muscle. Genetic studies revealed a G --> A transition at nucleotide position 80 in exon 1 of the Cav-3 gene (c.80G>A), generating a Arg --> Gln change at codon 27 (p.R27Q) of the amino acid chain in heterozygous state, while no mutation was found in unaffected members.

Signs of muscle hyperexcitability and hyperckemia at early ages may predict the development of a late onset autosomal dominant hand-involved myopathy associated to Cav-3 mutation in the family reported herein.