We report an apparently previously undescribed lethal skeletal dysplasia, c
linically resembling achondrogenesis, but with distinct radiologic and chon
dro-osseous morphologic features. These comprise bifid distal ends of the l
ong bones of the limbs, absent vertebral body ossification, a unique "baby
rattle" pelvic configuration with tall and broad ilia, absent endochondral
ossification, regions of mesenchymal cells within the resting cartilage, an
d abnormal mesenchymal ossification. (C) 2001 Wiley-Liss, Inc.