FGFR3-related condition: a skeletal dysplasia with similarities to thanatophoric dysplasia and SADDAN due to Lys650Met.

Mutations in the fibroblast growth factor receptor 3 (FGFR3) gene account for six related skeletal dysplasia conditions: achondroplasia, hypochondroplasia, thanatophoric dysplasia types 1 and 2, SADDAN (severe achondroplasia with developmental delay and acanthosis nigricans), and platyspondylic lethal skeletal dysplasia, San Diego type. This group of disorders has very characteristic clinical and radiologic features, which distinguish them from other skeletal dysplasias. They display a spectrum of severity in the skeletal findings, ranging from relatively mild hypochondroplasia to lethal thanatophoric dysplasia. We report a patient who has the missense FGFR3 mutation, Lys650Met, previously reported in association only with SADDAN, who exhibits some findings similar to both thanatophoric dysplasia (types 1 and 2) in addition to those findings characteristic of SADDAN.