Abstract: Objective To identify the pathogenic mutations in a family with piebaldism. Methods Clinical information and peripheral blood were collected from the patient with piebaldism and their parents. Whole exome sequencing was performed to identify the potential pathogenic mutations. QPCR was used to determine the deletion of the target gene, while gap-PCR and Sanger sequencing was used to determine the size and the specific deletion site. Results The proband had a heterozygous deletion mutation of approximately 1.74 Mb located at chromosome 4, including a full length of the pathogenic gene KIT for mottled disease and it was the smallest micro deletion causing isolated piebaldism due to the loss of the KIT. Conclusions The heterozygous deletion including the KIT is a potential cause of the piebaldism phenotype found in this family.

Key words: piebaldism, gene deletion, KIT, gene diagnosis, copy number variation(CNV)