PRNP octarepeat allele genotype frequencies among the modern and rare cattle breeds in Croatia

Prions cause a group of neurodegenerative disease such as the bovine spongiform encephalopathy (BSE) in cattle, scrapie in sheep, and Creutzfeldt-Jacob disease (CJD) in humans. The common feature of all transmissable spongiform encephalopathies (infectious, inherited and sporadic) is the aberrant metabolism of the prion protein (PrP). The gene encoding the prion protein in cattle has been assigned to a syntenic group U11, which is located on the chromosome 13 (BTA13). The PRNP gene extends over 20 kbp and a mRNA, consisting of three exons, is 4244 bp long. The only polymorphism in the bofine open reading frame (ORF) so far detected is a difference in a number of repeats of the octa/nona-peptides Pro-His-Gln-Gly-(Gly)-Gly-Gly-Trp-Gly-Gln. PRNP alleles containing five, six, or seven such elements are known. The PRNP octarepeat allele genotype vairations were analysed among the cattle in the USA, Belgium, Scotland and Switzerland. No major difference were detected among various modern cattle breeds, with an exception of Swiss Brown breed in Switzerland. The octarepeat variablity was not correlated to incidence of BSE in cattle although the homozygote with the allele containing five octarepeats have not been detected among the cattle with BSE.