Kniest-Like Dysplasia, Lethal

Clinical Features

Sconyers et al. (1983) described male and female offspring of nonconsanguineous parents who died in the neonatal period with a severe skeletal dysplasia that radiologically and histologically resembled Kniest syndrome but differed in clinical course and inheritance. Kniest syndrome (156550) is usually not lethal in the neonatal period and is inherited as an autosomal dominant. In the cases of Sconyers et al. (1983), x-rays showed dumbbell-shaped long bones superficially like those of Kniest dysplasia but with markedly shortened diaphyses and metaphyseal irregularities. Histologically, a 'Swiss cheese' appearance superficially like that of Kniest dysplasia was seen, but in addition distinctive changes were present in the growth plate and resting cartilage. By electron microscopy, the chondrocyte endoplasmic reticulum was found to have an appearance different from that observed in either normal or Kniest cartilage. Both pregnancies were complicated by polyhydramnios and both neonates were severely hydropic. Reference was made to another autosomal recessive Kniest-like dysplasia, the Rolland-Desbuquois syndrome (see 224400). For discussion of another Kniest-like dysplasia, see 245160.