Familial progressive hyper- and hypopigmentation: a report on a Chinese family and evidence for genetic heterogeneity

BACKGROUND: Familial progressive hyper- and hypopigmentation (FPHH) is a rare genodermatosis that is characterized by diffuse hyper- and hypopigmented spots on the skin and mucous membranes. It is caused by a pathogenic mutation of the KITLG gene. OBJECTIVES: To investigate the clinical features and mutation of the KITLG gene in a Chinese family with FPHH. METHODS: Histopathological and immunohistochemical analysis of lesions from the proband was performed. The KITLG gene was screened for the presence of mutations. RESULTS: A Chinese family containing 14 individuals with FPHH was described, and the proband was a 5-year-old girl showing diffuse hyper- and hypopigmented lesions on her extremities and trunk. Histopathological and immunohistochemical staining for S100 and HMB45 of skin biopsy specimens from the hyperpigmented areas showed a striking increase in melanin throughout the epidermis, especially in the basal cell layer, and staining of hypopigmented area specimens displayed lower levels of melanin in the epidermis. Mutation analysis of the KITLG gene was performed, but no mutation was found. STUDY LIMITATIONS: The new pathogenic gene was not found. CONCLUSION: A family with FPHH was described. Analysis revealed that its members did not have any mutations of the KITLG gene, which provided evidence for genetic heterogeneity of this genodermatosis.