Acanthosis nigricans (AN) has been reported in association with severe skeletal dysplasias due to activating mutations in FGFR3, including thanatophoric dysplasia, severe achondroplasia (ACH) with developmental delay and AN (SADDAN syndrome), and Crouzon syndrome with AN.
We report here the identification of a mutation in the transmembrane region of FGFR3, common to three unrelated patients with classical Crouzon syndrome and acanthosis nigricans, a dermatological condition associated with thickening and abnormal pigmentation of the skin.
The association of non-dwarfing and even non-skeletal conditions with FGFR3 mutations reveals the potential for a wide range of FGFR pleiotropic effects as well as locus heterogeneity in Crouzon syndrome.