Haplotypic diversity within the ovine calpastatin (CAST) gene

Calpastatin (CAST) is a protein inhibitor that acts specifically on calpains and plays a regulatory role in postmortem beef tenderization and muscle proteolysis. Polymorphisms in the bovine CAST gene have been associated with meat tenderness, but little is known about how the ovine CAST gene may affect sheep meat quality traits. In this study, we selected two parts of the ovine CAST gene that have been previously reported to be polymorphic (region 1-part of intron 5 and exon 6, and region 2-part of intron 12), to investigate haplotype diversity across an extended region of the ovine gene. First, we developed a simple and efficient polymerase chain reaction-single-strand conformational polymorphism (PCR-SSCP) method for genotyping region 2, which allowed the detection of a novel allele as well as the three previously reported alleles. Next, we genotyped both regions 1 and 2 of the ovine CAST gene from a large number of sheep to determine the haplotypes present. Nine different haplotypes were found across this extended region of the ovine CAST gene and four haplotypes were identified that suggested historical recombination events within this gene. Haplotypes are typically more informative than single nucleotide polymorphisms (SNPs) for analyzing associations between genes and complex production traits, such as meat tenderness, but the potential for intragenic recombination within the ovine CAST may make finding associations challenging.