B3GALT6 and spondyloepimetaphyseal dysplasia: B3GALT6 variants cause a single disorder that was alternatively described as spondyloepimetaphyseal dysplasia (SEMD) with joint hypermobility (SEMDJL1 or SEMDJL Beighton type; OMIM #271640) in the “Nosology and classification of genetic skeletal disorders: 2015 revision” [34,35,36,37,38,39,40,41,42,43] or as severe EDS-like disorder (OMIM #615349) because of the striking joint laxity and muscular hypotonia in infancy [44,45].