In light of our findings and given that genetic variants in the GDF5 association interval, as well as hip morphology, are risk factors for OA and DDH, we propose a developmental-genetic model in which risk-associated variants in downstream regulatory sequences influence local GDF5 expression levels in developing hip structures, leading to subtle alterations in hip morphology that, in turn, predispose the joint to injury and subsequent degeneration. The gene discussed is GDF5; the disease is Hip dysplasia.