Development of a Microsatellite Multiplex for Paternity Testing in Uruguayan Corriedale Sheep

Abstract

The Corriedale breed represents 70% of Uruguayan sheep stock, therefore it is important to guarantee accuracy in paternity assessment through DNA analysis, to contribute to genealogy recording and selection programs for economically relevant traits of the breed. In this study, a multiplex of 10 microsatellites (Short Tandem Repeats, STR) recommended from the ISAG (International Society of Animal Genetics) panel was developed. With this multiplex, a population of 156 Corriedale sheep was analyzed. The aim of this study was to evaluate the multiplex according to genetic variability of allele frequencies, for assigning parents through the their Probability of Exclusion (PE) values. The STR showed a relatively high variability according to the average Heterozygosity Index (HObs=0.661), the number of alleles observed (N=8.6), and the Polymorphic Information Content (PIC=0.614). In four ot the 10 STR (FCB20, TGLA53, MCM527 and MCM130) there was a loss of Hardy-Weinberg equilibrium due to the significant decrease of heterozygotes, with a consequent reduction of genetic variability. As a result, combined exclusion probability presented a value of 0.960. We conclude that in order to improve the accuracy in paternity diagnostic the multiplex could include a greater number of STR, given the low genetic variability present in the parents.