SMCHD1 and facioscapulohumeral muscular dystrophy: Facioscapulohumeral muscular dystrophy (FSHD), an autosomal dominant neuromuscular disorder, exists as two molecular subtypes: FSHD1 (95% of cases), defined by pathogenic contraction of the 4q35‐located D4Z4 macrosatellite repeat,1 and FSHD2 (5%), caused by loss‐of‐function mutations in chromatin‐modifying suppressors (e.g., SMCHD1, DNMT3B and LRIF1).2