Pacman dysplasia has characteristics of epiphyseal stippling and osteoclastic overactivity. It has been described in less than 10 patients but may be underdiagnosed. The syndrome may be inherited as an autosomal recessive trait. In order to make a definitive diagnosis, lysosomal storage should be investigated by electron microscopy, or enzyme assays should be performed. Familial recurrence can be easily detected by prenatal ultrasonography. This skeletal dysplasia is lethal.

The Torrance type of platyspondylic lethal skeletal dysplasia (PLSDT) is an autosomal dominant disorder characterized by varying platyspondyly, short ribs with anterior cupping, hypoplasia of the lower ilia with broad ischial and pubic bones, and shortening of the tubular bones with splayed and cupped metaphyses. Histology of the growth plate typically shows focal hypercellularity with slightly enlarged chondrocytes in the resting cartilage and relatively well-preserved columnar formation and ossification at the chondroosseous junction. Though generally lethal in the perinatal period, longer survival has been reported (summary by Zankl et al., 2005).

Greenberg dysplasia (GRBGD), also known as hydrops-ectopic calcification-moth-eaten (HEM) skeletal dysplasia, is a rare autosomal recessive osteochondrodysplasia characterized by gross fetal hydrops, severe shortening of all long bones with a moth-eaten radiographic appearance, platyspondyly, disorganization of chondroosseous calcification, and ectopic ossification centers. It is lethal in utero. Patient fibroblasts show increased levels of cholesta-8,14-dien-3-beta-ol, suggesting a defect of sterol metabolism (summary by Konstantinidou et al., 2008). Herman (2003) reviewed the cholesterol biosynthetic pathway and 6 disorders involving enzyme defects in postsqualene cholesterol biosynthesis: Smith-Lemli-Opitz syndrome (SLOS; 270400), desmosterolosis (602398), X-linked dominant chondrodysplasia punctata (CDPX2; 302960), CHILD syndrome (308050), lathosterolosis (607330), and HEM skeletal dysplasia.