We are grateful for Dr. Gorlin's comment on our report ''Atypical Radiological Findings in Achondroplasia With Uncommon Mutation of the Fibroblast Growth Factor Receptor-3 (FGFR-3) Gene (Gly to Cys Transition at Codon 375)' . Dr. Gorlin postulates that the atypical skeletal changes of the achondroplastic child (a 10-year-old boy) described in our report, including decrease in the height of the vertebral bodies to a greater extent than usual and exceptionally severe metaphyseal dysplasia, might not have been due to the uncommon mutation of the FGFR-3 gene (Gly375Cys) that he harbored, but rather signified a genetic combination of achondroplasia with an unknown bone disease that might have been transmitted from his father, who was described as short. As presented in the report, it was not possible to examine the father, and we are unable to address Dr. Gorlin's concern directly. However, we would like to present another case of atypical skeletal changes in an achondroplastic child who did not carry the common mutation of the FGFR-3 gene (Gly380Arg) . This additional example would suggest that uncommon mutations of the FGFR-3 gene may cause atypical skeletal changes in achondroplasia.
The patient was a Japanese boy and the second child of healthy, unrelated parents: a 38-year-old father and a 33-year-old mother. The family history was unremarkable except for sudden death of unknown cause of an elder brother of the patient at age 2 weeks. The patient was found to have short femora at 35 weeks of gestation on fetal ultrasonography, but was delivered normally at term. Birth length was 46.0 cm (-2.0 SD), weight 2,986 g (-0.5 SD), and OFC 33.0 cm (-0.4 SD). The face appeared unremarkable. Although mild micromelia was suspected, radiographic examination was not carried out at this time. Thereafter, rhizomelia became evident, and trident hands were noted. A skeletal survey at age 6 months disclosed radiologic changes consistent with those in achondroplasia, including nar-