The human FGFR3 gene carrying a glycine to arginine subsitution at amino acid 380 (G380R), a mutation found in the majority of achondroplasia patients, was fused to the mouse Fgfr3 promoter and first non-coding exon (-2311 to +156) and used as the transgene. RT-PCR analysis showed transgene expression in 16 day chondrocytes from transgenic embryos. The transgene expression pattern is similar to that of the endogenous protein as demonstrated by in situ hybridization analysis.