Genetic variation in the 5'UTR of the KRT2.13 gene of sheep

KRT2.13 is a type II keratin wool intermediate filament (IF) protein. Extensive variation was revealed in the 5' untranslated region (UTR) of the ovine KRT2.13 gene (KRT2.13) using polymerase chain reaction - single strand conformational polymorphism (PCR-SSCP) analysis. Nine unique PCR-SSCP patterns were obtained with individual sheep having either one (homozygous), or a combination of two (heterozygous) of these patterns. Seven of the amplicons that produced the apparently homozygous patterns were successfully sequenced (GenBank FJ217670 - FJ217676), revealing eight single nucleotide insertions, 10 single nucleotide substitutions, a nucleotide deletion and a 16 nucleotide insertion that occurred in only one of the sequences. The seven sequences showed between 85% and 95% homology to the previously identified KRT2.13 sequence (GenBank X72379). This study emphasizes the power of PCR-SSCP analysis in genotyping, as this extensive variation was found in only 100 sheep, of a variety of breeds. Since variation in the 5'UTR of genes may affect their expression, this genetic variation needs to be further studied to establish its role if any, in influencing gene expression and consequently wool traits.