MITF gene variations in Turkish Van cats and its association with eyes color

The variation in eye color observed in Turkish Van cats is defined as heterochromia iridum (HI), a trait that also appears as a clinical indicator of Waardenburg syndrome in humans. Genetic studies in humans and several animal species have shown that mutations in the MITF gene can lead to HI, skin depigmentation, and deafness. However, MITF gene variations and their potential association with HI have not yet been investigated in Turkish Van cats or other white cat breeds. In this study, buccal swab samples were collected from a total of 120 Van cats—40 amber–amber, 40 blue–blue, and 40 odd-eyed (blue–amber) reared at the Van Cat Research and Application Center, and genomic DNA was isolated. Individual DNA samples from 12 individuals per group, as well as three pooled DNA samples composed of DNA from 28 Van cats per group, were prepared. Using the Sanger DNA sequencing method, mutation screening was performed in the promoter region and the DNA sequences encoding the HLH-LZ region of the MITF gene, and target SNPs were selected for further analyses. Further genotyping of the selected SNPs was performed using PCR-HRM and PCR-RFLP techniques, and the association of these SNPs with HI was investigated. In the HLH-LZ region of the MITF gene, the intronic c.809-101 A>G, c.809-284 C>T, c.922+27 G>A, c.922+92 C>A, and c.1071-20 A>T SNPs were identified, while -593 C>G, -476 T>C, -445 G>A, -250 T>C, -129 C>T, and -25 T>C SNPs were detected in the promoter region. Among these variants, the promoter -129 C>T and -250 T>C SNPs were considered potentially associated with HI and were selected for further analysis. The selected SNPs were genotyped in 84 cats using PCR-HRM or PCR-RFLP methods, and together with the obtained data, genotypes for these two variants were determined in all 120 Van cats. Evaluation of the genotypes and their combinations revealed no statistically significant association with eye color phenotypes. In addition, haplotype analyses of these two SNPs were performed. The -129 C>T and -250 T>C SNP haplotypes were found to be potentially associated with HI in Van cats (p = 0.051). Overall, the results indicate that no variants affecting protein structure were present in either the exon sequences or splice sites of the HLH-LZ region of the MITF gene in Turkish Van cats. However, the polymorphisms identified in the promoter region of the MITF gene may influence its transcriptional activity. These variations may play an important role in the development of phenotypic characteristics in Turkish Van cats and may represent significant genetic differences distinguishing Turkish Van cats from non-white cat populations.