Abstract: 【Abstract】 A pedigree with familial acanthosis nigricans presenting with atypical clinical symptoms was reported. The 4-year-old female proband began to develop black patches on the neck and abdomen since the age of 1 year, which had gradually spread to the lips and front of the trunk in recent years. Reflectance confocal microscopy of the abdominal skin showed downward extension and twisting of dermal papillary rings with formation of gully structure, and moderately to highly refractive particles in the dermal papillary rings. The proband′s father and grandmother had similar medical history, but the pigmentation spontaneously subsided with age, leaving only local thickened skin lines. Peripheral blood samples were collected from the proband, her parents and grandmother, and panel-based targeted sequencing was performed on the peripheral blood DNA of the proband. Sequencing showed a missense mutation c.1949A>C （p.Lys650Thr） in exon 14 of the FGFR3 gene in the proband, and Sanger sequencing confirmed the presence of this mutation in the proband and her father and grandmother. A diagnosis of familial acanthosis nigricans was made.

Key words: Acanthosis nigricans, Receptor, fibroblast growth factor, type 3, Mutation, Targeted sequencing