Thanatophoric dysplasia: roentgenographic findings and detection of a de novo mutation of FGFR3 gene in a Thai patient.

Thanatophoric dysplasia is the most common neonatal lethal skeletal dysplasia with an estimated incidence of 1 in 20,000 live births. This condition shares some similarity of radiological findings with other types of lethal skeletal dysplasias. Definite diagnosis is necessary for accurate medical and genetic counseling. The authors describe a male neonate who had characteristic features of thanatophoric dysplasia type I including severe shortening of limbs with redundant skin folds, large head, frontal bossing, depressed nasal bridge, and narrow thoracic cage with severe respiratory insufficiency. Postmortem radiographs revealed short ribs, flat vertebral bodies (platyspondyly), hypoplastic iliac bones, marked shortening of long bones including short and mild bowing of both femora, oval radiolucent area of proximal femur. Molecular analysis of Fibroblast Growth Factor Receptor 3 (FGFR3) gene identified a de novo mutation, p.R248C, in exon 7.