Some patients with mutations of the FGFR3 gene will develop the SADDAN syndrome - severe achondroplasia, developmental delay and acanthosis nigricans.
Chromosome affected: 4p16.3
Gene affected: fibroblast growth factor receptor 3 (FGFR3)
Clinical features of SADDAN:
(1) achondroplasia
(2) developmental delay, mental retardation
(3) acanthosis nigricans
The differential diagnosis includes Muenke syndrome and Couzon syndrome with acanthosis nigricans. which also affects FGFR3.
