Some patients presenting with symptoms resembling facioscapulohumeral dystrophy (FSHD) do not harbour the typical D4Z4 repeat contraction on chromosome 4q35. We investigated the genetic defect in 16 such patients and identified one patient carrying a complex rearrangement in the FSHD locus which could not be identified by standard analysis, one patient had somatic mosaicism for the D4Z4 contraction, six had hypomethylation of D4Z4 (FSHD2), four had CAPN3 mutations, and two had a VCP mutation. In two patients a specific genetic was not identified.
These data were useful to develop a diagnostic algorithm for patients presenting with a FSHD-like disorder. (By Dr. Sabrina SACCONI, http://jmg.bmj.com/content/early/2011/10/07/jmedgenet-2011-100101.abstract?papetoc )