Prion protein gene polymorphisms in Turkish native goat breeds

Abstract

Susceptibility to 'scrapie' disease in goats is influenced by polymorphisms of the prion protein (PRNP) gene. The aim of this study was to identify PRNP gene polymorphisms in a total of 356 scrapie disease-free goats from 10 Turkish native breeds. Eighteen single-nucleotide polymorphisms were detected in the caprine PRNP open-reading frame. Ten previously described amino acid substitutions (I142M, H143R, N146S, N146D, R151H, R154H, P168Q, R211Q, Q222K and P240S) and two novel dimorphisms (G134E and Q163P) were identified. The strongest association between caprine PRNP and relative resistance to scrapie disease has been reported previously for polymorphisms at codons 146 (S/D) and 222 (K). In the present study, these three PrP variants were relatively rare with 6.3%. This is the first report on PRNP gene variation in Turkish native goat breeds and our knowledge of these polymorphisms will assist goat breeding programmes to reduce the risk of scrapie.

Genetic profile of scrapie codons 146, 211 and 222 in the PRNP gene locus in three breeds of dairy goats

“…Results from our comparisons suggest that geographical origin of the breeds combined with population structure, breeding schemes and scrapie incidence seem to be the key determinants of the PRNP gene profile. Thus, the studied breeds shared similar haplotypic frequencies with many goat breeds reared in neighboring Mediterranean countries, such as certain breeds in Southern Italy (Maltese, Ionica and Red Mediterranean) [ 27 ] and Turkey (Saanen, Akkeci and Kilis) [ 32 ]. However, significant genetic distances were also detected in respect to some other breeds reared in neighboring countries.…”

“…The present study confirms that the dairy goat population in Greece, collectively represented here by the three studied breeds, is one of the very few worldwide where all scrapie resistance-associated alleles in the three codons (146, 211 and 222) have been detected. Previous research in Turkey has also reported presence of all these alleles in the goat population; however, much lower frequencies have been reported for alleles 222K and 211Q [ 32 ]. Polymorphic variation in the PRNP gene locus reported in our study enables the design and implementation of breeding programs towards enhanced scrapie resistance in goats reared in Greece.…”

“…According to previous research, allelic frequencies vary across countries and breeds [ 13 , 24 – 32 ]. Results from our comparisons suggest that geographical origin of the breeds combined with population structure, breeding schemes and scrapie incidence seem to be the key determinants of the PRNP gene profile.…”

“…In Damascus goats of Turkey, allele 146D was not detected, but a much higher frequency of 146S ( ca . 28.0%) was reported [ 32 ]. Moreover, alleles 211Q and 222K were detected for the first time in Damascus goats of Greece.…”

“…The notion is that success of such programs is subject to in-depth knowledge of the frequency and distribution of PRNP polymorphisms conferring resistance to classical scrapie [ 14 , 23 ]. Different estimates of allelic frequency have been published for breeds in China [ 24 ], Japan [ 25 ], USA [ 26 ], Italy [ 27 – 29 ], France [ 13 ], UK [ 30 ], Cyprus [ 31 ] and Turkey [ 32 ]. Given the observed differences between countries and breeds, EFSA concluded that any selective breeding programs should be developed and managed at national level, and in each case, the frequency of the resistance-associated alleles and haplotypes should be assessed for each breed of interest [ 23 ].…”