Peibaldism refers to

Piebaldism is an uncommon congenital autosomal dominant, stable patterned leukoderma characterized by a frontal, median or paramedian depigmented patch with a white forelock. There are also macules with scattered hyperpigmented islets. Mutations in the KIT gene on chromosome 14 are the cause. A white forelock on a white triangular elongated or diamond- shaped macule on the forehead from bih is the classical feature in 80%-90%of cases. It is due to defect in migration of melanoblasts from neural crest to skin and hair follicles. melanocytes and melanin are absent at the site of lesions IADVL textbook of dermatology , pigmentary disorders , page 743