PIEBALDISM

Piebaldism is caused by mutations in the KIT protooncogene. Stimulation of the KIT receptor tyrosine kinase by its ligand, stem cell factor/KIT ligand, results in the phosphorylation of MITF and potentiation of MITF activity. This relationship between the KIT receptor and MITF, as a final common effector of melanocyte survival during development, is likely to explain the developmental patchy loss of melanocytes occurring in human piebaldism when KIT receptor function is compromised.

Patients with piebaldism generally have depigmented patches on the ventral or lateral trunk and/or the mid-extremities, with the hands and feet spared. Poliosis is a common feature. The depigmented patches tend to be larger than those observed in WS. Typically piebaldism is not associated with deafness, although piebaldism with deafness, otherwise referred to as Woolf syndrome, has been molecularly confirmed.