Characterization of Mutations at Nucleotide 1138 of the Fibroblast Growth Factor Receptor 3 Gene in Filipino Patients with Achondroplasia
Introduction. Achondroplasia is the most common form of short limbed dwarfism with a birth incidence between 1:7,500 and 1:70,000. In >97% of cases, this autosomal dominant disorder is associated with a G to A or a G to C mutation at nucleotide 1138 in exon 10 of the fibroblast growth factor receptor 3 (FGFR3) gene. Both mutations result in the substitution of a glycine (Gly) to arginine (Arg) residue at position 380 in the transmembrane domain of the FGFR3 protein.
Methods. To assess the presence of this mutation in 11 unrelated Filipino patients with achondroplasia, RFLP digestion of their PCR amplified genomic DNA was done. The PCR products were digested with the restriction enzymes SfcI and MspI to determine the G1138A transition and the G1138C transversion, respectively.
Results. We report that ten of the 11 patients were heterozygous for the G to A mutation. Only one patient had the G to C mutation in the same position.
Conclusion. Majority of Filipino patients with achondroplasia have the same mutation most often defined in patients with achondroplasia from other countries. This further supports that the majority of patients with achondroplasia have a Gly to Arg substitution caused by a G to A change at nt 1138 of the FGFR3 gene.