PrP genotype variation in cattle and incidence of BSE

The cattle disease bovine spongiform encephalopathy (BSE) is one of a family of similar diseases known as transmissible spongiform encephalopathies (TSEs) which affect various mammals. Polymorphisms and mutations of the PrP gene have been associated with incidence of experimentally induced and natural TSEs in sheep, goats, laboratory mice and humans and so this study of the bovine PrP gene was undertaken to discover if there was a similar PrP genotype association with BSE in affected cattle. Although the sheep and human PrP genes are highly polymorphic, the bovine PrP gene is, in comparison, remarkably invariant. There are two polymorphisms of the coding region of the bovine PrP gene, in particular a difference in the number of an octapeptide repeated sequence (either 5 or 6 copies). Analysis of more than 350 cattle in Scotland revealed no frequency differences between the PrP genotypes of BSE and healthy cattle. There is therefore, no PrP marker which could be used to predict which cattle are at risk of developing BSE.