Age at onset–dependent presentations of premature hip osteoarthritis, avascular necrosis of the femoral head, or Legg‐Calvé‐Perthes disease in a single family, consequent upon a p.Gly1170Ser mutation of <i>COL2A1</i>

The p.Gly1170Ser mutation of COL2A1 in the family described is responsible for pathology confined to the hip joint, which presents as isolated precocious hip OA, AVN of the femoral head, or Legg-Calvé-Perthes disease. Age at onset in relation to closure of the femoral head epiphysis appears to be a critical factor in determining disease pattern.