A glycine 375-to-cysteine substitution in the transmembrane domain of the fibroblast growth factor receptor-3 in a newborn with achondroplasia.

Achondroplasia, the most common form of chondrodysplasia, has been associated with mutations in the gene of the fibroblast growth factor receptor-3 (FGFR-3) on chromosome 4p. All 39 achondroplasia alleles studied so far carried point mutations which caused the same amino acid exchange, a substitution of glycine by arginine at position 380 (G380R) in the transmembrane domain of the receptor. We report on a newborn with achondroplasia who does not carry a G380R mutation but has a mutation causing substitution of a nearby glycine with a cysteine (G375C). This observation indicates allelic heterogeneity and confirms the role of mutations in the transmembrane domain of FGFR-3 in the pathogenesis of achondroplasia.