ACAN and spondyloepimetaphyseal dysplasia, matrilin-3 type: In particular, an allelic series of ACAN mutations have been identified that result in a broad phenotypic spectrum including spondyloepimetaphyseal dysplasia (SEMD) [12], spondyloepiphyseal dysplasia Kimberley type (SED) [13], familial osteochondritis dissecans [14] and various undefined short stature syndromes associated with accelerated bone maturation [15] (Table 1).