While differing from previous findings, likely because in vitro conditions do not fully recapitulate the in vivo complexity, they are consistent with impaired chondrocyte differentiation at all stages of maturation and with striking clinical similarities between ACH and Campomelic Dysplasia, which is due to SOX9 haploinsufficiency (40, 41). The gene discussed is SOX9; the disease is campomelic dysplasia.