Determination of PRNP polymorphism gene and genetic characteristics in cats

Transmissible Spongiform Encephalopathies (TSEs) are contagious, fatal neurodegenerative disorders affecting both humans and animals, resulting from the misfolding of prion protein. In some species, variations in the prion protein gene (PRNP) have been associated with susceptibility to prion diseases. To date, there are limited studies investigating prion protein in domestic cats. Therefore, this study aimed to identify feline PRNP polymorphisms in randomly bred cats. For this purpose, DNA isolation, PCR and amplicon sequencing were performed in 74 cat samples collected from Türkiye to detect PRNP gene variants. A total of 10 polymorphisms were observed, including nine SNPs and a 27 bp in/del polymorphism in the tandem repeat region. Three of these SNPs (c.201C>A, c.225C>T and c.228A>C) were identified for the first time. All SNPs in the open reading frame are synonymous and do not cause amino acid variation in the prion protein sequence. Allele and genotype frequencies of polymorphisms were calculated, and chi-square test was performed to calculate the compliance with Hardy-Weinberg equilibrium for each locus. Haplotype estimation and frequency calculation were performed using these data, and a total of 28 haplotypes were observed. Eight main haplotypes with frequencies greater than or equal to 0.05 were found. A network was created for haplotypes. Linkage disequilibrium between SNPs in the cat PRNP gene was calculated and a statistically significant, non-random relationship was observed between six locus. R2 values were calculated and a heat map was created according to these values. Accordingly; 10 SNPs are located in a 0.8 kb region. Of the 10 SNPs determined; It is seen that c.201C>A is in LD with c.171C>T and c.264T>C with lower R2 values. According to the heat map; R2 values greater than 0.5 were calculated between c.171C>T and c.264T>C, and c.- 3G>A and c.797G>A. No other correlation was observed between SNPs. The findings show that prion protein is conserved in cats in northwestern Türkiye, unlike populations in other regions of Turkey, and that there are possible PRNP gene differences between geographically close groups.