A novel KITLG mutation detected only in the lesion of linear and whorled nevoid hypermelanosis

Linear and whorled nevoid hypermelanosis (LWNH) is characterized by hyperpigmentation following Blaschkos line. The lesions usually occur in infancy or early childhood and are asymptomatic and progress with age. The affected individuals have no accompanying extracutaneous manifestations. Most recently, a postzygotic mutation in the KITLG gene is identified on skin from a patient with LWNH. KIT-ligand (KITLG), also known as stem cell factor, is a ligand for the tyrosine kinase c-KIT receptor that acts exclusively in a melanocyte-autonomous manner. In this study, we show a patient with typical LWNH who have a novel heterozygous missense mutation, c.325G>A (Asp109Asn) in KITLG only in the epidermis of hyperpigmented lesion. On the other hand, the missense mutation is not identified in the normal skin. These results clearly indicate that the hyperpigmented lesions are caused by the missense mutation in KITLG.