Atelosteogenesis type I: autopsy findings.

We have documented the clinical, radiologic, and autopsy findings of 2 fetuses with atelosteogenesis type I, aged 22 and 17 weeks. This rare autosomal dominant lethal skeletal dysplasia is caused by mutation in the FNLB gene. The 17-week-old fetus had some features of atelosteogenesis type II, notably "hitchhiker thumbs," a cleft palate, and midfacial flattening.