Genetic variation analysis in three cases of piebaldism and analysis of the genotype-phenotype relationship / 中华皮肤科杂志

ABSTRACT

Objective:To identify pathogenic genes in 3 cases of piebaldism, and to explore the genotype-phenotype relationships in piebaldism.Methods:Clinical data were collected from 3 patients with piebaldism and their parents at the Department of Dermatology, Henan Provincial People′s Hospital from January 2019 to December 2021. Peripheral blood samples were obtained from them and 100 unrelated healthy controls, and DNA was extracted. Whole-exome sequencing technology was used to screen genetic variation sites, and then Sanger sequencing was performed for verification. The deleteriousness of genetic variants was evaluated by using pathogenicity analysis software tools.Results:Case 1: a 23-year-old male patient presented with white patches on the forehead, chest, and abdomen for 23 years, and his parents had no similar symptoms; case 2: a 1-year- and 5-month-old male infant presented with white patches on the forehead and abdomen for 1 year, and his parents had no similar symptoms; case 3: a 6-year-old male child presented with white patches on the forehead and limbs for 6 years, and his parents had no similar clinical manifestations. Genetic testing showed that a missense mutation c.2033T>C (p.L678P) in exon 14 of the KIT gene, a splice site mutation c.2485-1G>C in exon 18 of the KIT gene, and a heterozygous missense mutation c.2346C>G (p.F782L) in exon 16 of the KIT gene were identified in the case 1, 2, 3 respectively, but no above mutations were identified in the patients′ parents or 100 unrelated healthy controls. The 3 genetic variants were all novel pathogenic mutations, and all were deleterious mutations.Conclusions:Three novel pathogenic mutations in the KIT gene were identified in the 3 cases of piebaldism, namely c.2033T>C (p.L678P), c.2485-1G>C, and c.2346C>G (p.F782L). It was further verified that the severity of piebaldism was closely related to the type and location of KIT gene mutations.