COL2A1 and spondyloepiphyseal dysplasia: Spondyloepiphyseal dysplasia was suspected due to the combination of proximal femoral epiphyseal abnormalities, odontoid hypoplasia (Fig. 4), and platyspondyly, but genetic sequencing and deletion/duplication studies of COL2A1 (collagen type II alpha 1) and SEDL (spondyloepiphyseal dysplasia tarda) were negative.