Evaluation of the facioscapulohumeral muscular dystrophy (FSHD1) phenotypein correlation to the concurrence of 4q35 and 10q26 fragments

Probe p13E-11 (locus D4F104S1) detects two highly homologous polymorphic lo ci on chromosomes 4q35 and 10q26. Previous reports in the literature have d escribed a correlation of shortened 4q35-specific fragments and facioscapul ohumeral muscular dystrophy (FSHD1). We have identified 30 FSHD1 families ( 46 patients) carrying one short 4q35 and one short 10q26 fragment. The clin ical data of these patients were compared with those of 47 families (131 pa tients) showing a single short 4q35 fragment, in order to evaluate a potent ially modifying influence of shortened 10q26 fragments on the phenotype. Ac cording to our results, the polymorphic locus on 10q26 does not modify the FSHD1 phenotype. The normal population (14%) and our FSHD1 population (13%) did not significantly differ in the overall frequency of short polymorphic 10q26 fragments. The specificity of the p13E-11:EtoRI - BlnI test for FSHD 1 was 100%.