Genotype and phenotype study of 34 Spanish patients diagnosed with oculopharyngeal muscular dystrophy

Oculopharyngeal muscular dystrophy is an autosomal dominant adult-onset disease with several clinical features. The genetic cause is an expanded (GCN)n mutation coding for polyalanine. Severity and the age of onset are variable and may depend on the size of the unstable triplet. Our objectives were to correlate the genotypic and phenotypic features in 34 affected patients, and to complete the molecular analysis for a control Spanish population in order to confirm the (GCN)n polymorphism frequency observed in other populations. We found a correlation between impaired CPK levels and sex. No statistical differences were found when comparing the length in triplet expansion and other variables. The (GCN)n polymorphism’s frequency observed in other countries could not be proven in ours. Moreover, no correlation was observed amongst the size of the mutation, the age of onset, and the phenotype. This fact suggests that other conditions apart from the already known genotype could influence the age of onset and the severity of the symptoms.