Piebaldism is an autosomal dominant genetic disorder of pigmentation 
characterized by white patches of skin and hair. Melanocytes are lacking in 
these hypopigmented regions, the result of mutations of the KIT gene, which 
encodes the cell surface receptor for steel factor (SLF). We describe the 
analysis of 26 unrelated patients with piebaldism-like hypopigmentation--17 
typical patients, 5 with atypical clinical features or family histories, and 4 
with other disorders that involve white spotting. We identified novel pathologic 
mutations or deletions of the KIT gene in 10 (59%) of the typical patients, and 
in 2 (40%) of the atypical patients. Overall, we have identified pathologic KIT 
gene mutations in 21 (75%) of 28 unrelated patients with typical piebaldism we 
have studied. Of the patients without apparent KIT mutations, none have apparent 
abnormalities of the gene encoding SLF itself (MGF), and genetic linkage 
analyses in two of these families are suggestive of linkage of the piebald 
phenotype to KIT. Thus, most patients with typical piebaldism appear to have 
abnormalities of the KIT gene.