OBJECTIVE[corrected] To investigate the mutation at the transmembrane domain of fibroblast growth factor receptor 3 (FGFR3) nucleotide 1138 site for identifying the major pathologic mechanism of achondroplasia (ACH) and to evaluate the efficacy of denaturing gradient gel electrophoresis(DGGE) method for screening the point mutations.

METHODSThe genomic DNA from 17 clinically diagnosed ACH patients where analysed by polymerase chain reaction-restriction fragment length polymorphism(PCR-RFLP) with Sfc I and Msp I restriction endonucleases and by PCR-DGGE technique for screening.

RESULTSG to A transition mutation at nucleotide 1138 was detected in 14/17 of the ACH patients as heterozygotes by PCR-RFLP with Sfc I digestion. No 1138 G to C transition was detected by Msp I digestion. All of the 14 samples with G to A mutation were also found to be positive for point mutation by PCR-DGGE. No mutation was detected in 3 negative samples by PCR-RFLP, implying that there was actually no point mutation in this amplified region.

CONCLUSIONNucleotide 1138 in transmembrane domain of FGFR3 gene is the hot point for mutation in ACH and hence its major pathologic cause. PCR-DGGE is a sensitive and reliable technique for point mutation screening, especially for the heterozygotes.