The limb bones were short, straight and had metaphyseal flaring and cupping. Histologically, the epiphyseal cartilage was lobulated and had increased vascularity. The chondrocytes were ballooned and there was little intervening matrix. There was disorganization of chondrocyte column formation in the growth zone and there was severe disturbance of enchondral ossification. The chondrocytes had large lacunae, some of which were filled with loose fibrillar material.
Most affected fetuses die in utero or shortly after delivery.
The reported incidence is 1 in 40,000 births. However, a recent report of an affected infant heterozygous for a mutation in the COL2A1 gene may represent a case in which a new dominant mutation is responsible for the condition. Thus, molecular studies may help to elucidate inheritance pattern and recurrence risk. Prenatal diagnosis through transvaginal ultrasound evaluation may be possible as early as 12 weeks of gestation. Prenatal Diagnosis, Vol.13, 523-528.