Spondyloepiphyseal dysplasia congenita (SEDC, OMIM 183900) is a common subtype of the type II collagenopathies, a heterogeneous group of chondrodysplasias resulting from mutations in the collagen type II alpha-1 gene (COL2A1, OMIM 120140) [1]. The gene discussed is COL2A1; the disease is type 2 collagenopathy.