Furthermore, a Japanese boy with insulin resistance and acanthosis nigricans was found to be heterozygous for a mutation of the insulin receptor gene that resulted in the replacement of glycine-996 with valine in the ATP binding site of the receptor.
Early development of extensive acanthosis nigricans (AN) is a key feature in some patients who have hypochondroplasia (HCH) in association with FGFR3 mutations.
Acanthosis nigricans with high fasting insulin levels in the proband suggested severe insulin resistance and prompted INSR gene sequencing, which revealed the novel, heterozygous p.Phe1213Leu mutation in the patient and his family members.
Crouzon syndrome with acanthosis nigricans (CAN) is caused by a mutation in the fibroblast growth factor receptor ( FGFR) 3 gene that presents clinically as Crouzonoid craniofacial features in association with other anomalies such as acanthosis nigricans and benign odontogenic tumors.
Familial acanthosis nigricans caused by the mutation of the fibroblast growth factor receptor 3 (FGFR3) gene is characterized by short stature, hypochondroplasia and acanthosis nigricans.
Besides the expansion of the phenotypic spectrum of FGFR3-related OCDs to HCH with AN, this observation underscores the continuing adverse effect of this specific mutation upon the normal inhibitory signaling of the receptor at least in epidermal cells.
Germline mutations of the FGF receptor 3 (FGFR3) cause autosomal dominant skeletal disorders such as achondroplasia and thanatophoric dysplasia, which can be associated with acanthosis nigricans of the skin.
By contrast, a larger group of insulin-resistant patients who were obese with hyperandrogenism, insulin resistance, and acanthosis nigricans (HAIR-AN syndrome) did not have a high probability of mutations in the insulin receptor.