The Study On Skin Pigmentation And Hypopigmentation Syndrome Caused By De Novo Mutation In KITLG Gene

Objectives: This study is a patient with clinically suspected familial progressive hyperpigmentation and hypopigmentation(FPHH)and whole exon sequencing to identify mutation.Functional analysis,cellular mechanism research and animal model research on the discovered KITLG gene mutation.To understand the pathogenicity and pathogenesis of this mutation site.Methods: Clinical case diagnosed through whole exon sequencing and patient skin pathology testing,amino acid conservation,protein structure prediction,and pathogenicity prediction of the mutation site were analyzed by bioinformatics.ABE single-base editing and construction of overexpression plasmids were used to analyze changes in its function at the cellular level.RNA-seq found differential genes in the melanin pathway and analyzed their expression changes.To further study the pathogenic mechanism of this mutation at the level of transgenic mice.Results: The results showed that the patient had the mutation c.329A>G in the KITLG gene.The skin pathology test showed melanosis in the basal layer.Bioinformatics analysis showed that the amino acid at this site was relatively conservative,and the protein structure changed after the site mutation.The pathogenicity prediction suggested that it might be pathogenic.The results of the construction of the over-expression plasmids showed that,compared to the wild type,the expression of the mutant at the m RNA and protein levels was significantly down-regulated.After single-base editing,compared to wild-type cells,the expression of homozygous cells was significantly upregulated at the m RNA level,while the expression of heterozygous cells was significantly down-regulated.After UV irradiation stimulation,the expression of the three types of cells was up-regulated,with a significant difference.At the protein level,compared to wild-type cells,the expression of homozygous cells was significantly upregulated,while the expression of heterozygous cells was no significantly difference.After UV irradiation,the expression of the three types of cells was up-regulated,but the difference was not significant.At the melanin level,compared to wild-type cells,the melanin content of homozygous cells was down-regulated,while the expression of heterozygous cells increased,with no significant difference.After UV irradiation,the melanin content of all three types of cells was up-regulated,and there was a significant difference between homozygous cells and wild-type cells,while there was no significant difference between heterozygous cells and wild-type cells.RNA-seq results showed that the expression of the differential gene MITF was significantly up-regulated in homozygous cells,while the difference in the expression of heterozygous cells was not significant.The expression of melanin synthesis key genes TYR,TYRP1,and TYRP2 in A375 cell are relatively low.Conclusions: The research results indicate that the KITLG c.329A>G mutation site has pathogenicity and is associated with FPHH disease.It also preliminarily explored the pathogenic mechanism of this mutation,providing a reference for finding new therapeutic approaches for diseases caused by KITLG gene mutations in the future,which has important clinical significance.