Thanatophoric dysplasia type I with syndactyly.

We report on a case of thanatophoric dysplasia type 1 (TD1) due to a Tyr373Cys mutation in the fibroblast growth factor receptor 3 (FGFR3) gene with soft tissue syndactyly of the fingers and toes. Syndactyly has not been previously described in TD or other conditions with FGFR3 mutations, but occurs in several craniosynostosis syndromes due to mutations in FGFR2. We conclude that mutations in FGFR3 may also be associated with developmental abnormalities due to interference with programmed cell death.