Single nucleotide polymorphisms in the equine transferrin gene

Single nucleotide polymorphisms (SNPs) in exons 13, 15 and 16 of equine transferrin for common, rare and mutant variants were investigated. Compared with previous work a further 13 SNPs have been identified, allowing for the two previously identified clades to be subdivided into 11 groups. A combination of one or more of eight SNPs can be used to classify the equine variants into these 11 groups, since most are co-inherited. Putative sites of glycosylation in exons 13 and 16 showed no polymorphism, suggesting that presence or absence of sugar moieties does not lead to electrophoretic variation between the variants. Using the 26 SNPs currently identified in transferrin it is still not possible to differentiate variants F1 from F2, or D from H2, which represent 75% of the variants occurring in Thoroughbred equine population. This suggests that further SNPs exist in equine transferrin. The significance of the high level of variation in exon 15 is discussed.