ABSTRACT
BACKGROUND: Achondroplasia is the most common form of dwarfism. The achondroplasia class consists of achondroplasia, thanatophoric dysplasia and hypochondroplasia. Clinical symptoms are variable, but the common gene, fibroblast growth factor receptor 3 (FGFR3), could account for these variable conditions. We tried to isolate the molecular defects in Korean patients with achondroplasia and hypochondroplasia. METHODS: The sites frequently mutated (G380R and N540K) of the FGFR3 gene of seventeen Korean patients with skeletal dysplasia (16 cases of achondroplasia and one of hypochondroplasia) were analyzed by PCR-RFLP and confirmed by direct sequencing. RESULTS: Missense mutations, which cause G380R of the FGFR3, were present in 15/16 (93.7%) achondroplasia patients. Among these, G to A transition was found in 14 of the 15 (93.3%) patients, and a G to C transversion in a single (6.6%) patient. One case did not show any mutation of the FGFR3 gene reported in achondroplasia, including G375C. A patient with suspected hypochondroplasia exhibited the common C to G transversion mutation, resulting in N540K. CONCLUSIONS: The mutations at codons 380 and 540 of the FGFR3 gene were also found to be common causative mutations of achondroplasia and hypochondroplasia, respectively, in Koreans. These mutations could be used as the target of molecular diagnosis. Based on this simple molecular study, genetic counseling for skeletal dysplasia and prenatal diagnosis will be possible.