SMCHD1 and facioscapulohumeral muscular dystrophy: Considering that these D4Z4 homologs are not associated with FSHD or epigenetically altered in the disease [49], any inclusion of these sequences further complicates the methylation analysis, as it further dilutes the signal from the contracted 4qA allele (important for FSHD1) and also dilutes the signal from combined 4q/10q alleles (important for FSHD2).