Dyssegmental dwarfism: a new syndrome of lethal dwarfism.

Dyssegmental dwarfism is an autosomal, recessively inherited, lethal, generalized chondrodysplasia characterized by micromelia, cleft palate, and variable limited mobility at the elbow, wrist, hip, knee, and ankle joints and, in some cases, by occipital encephalocele, inguinal hernia, hydronephrosis, hydrocephalus, and patent ductus arteriosus. Roentgenographically, there is a marked variation in the size of all vertebrae with some anterior wedging, coronal clefts, and lack of caudal interpediculate widening. In addition, there are short, broad tubular bones with metaphyseal widening, variable bowing of the tibia, fistula, femur, radius, and minimally the ulna. In the feet, the talus and calcaneus are poorly modeled, and the 1st metatarsal and 1st proximal phalanx are enlarged. The striking similarities among these cases, as well as the others in the literature, argue strongly for their being a common defect in embryogenesis. However, there is also evidence of heterogeneity. Our case reported here has distinct hypoplasia of the scapulae, absence of carpal ossification centers, and lack of flaring of the ilia, whereas the other cases show well-developed scapulas, accelerated carpal bone maturation, and a wide-flared ilia.