First exploratory GWAS of parasite resistance in Pelibuey sheep identifying biologically plausible candidate loci.

The aim of this study was to detect genomic regions and genes associated with gastrointestinal nematodes (GIN) resistance in Pelibuey sheep, based in deworming necessity (NOD) estimated by fecal egg count (FEC). During a ten-months period, deworming criterion was based on GIN eggs per gram (EPG), then animals exceeding 1000 EPG were dewormed, and individuals were classified as cases (dewormed at least once) or controls (non-deworming at all). Animals were genotyped with the GGP Ovine50k genome profiler microarray. Quality control of dataset and case-control GWAS were carried to identify associated candidate genes and quantitative trait loci (QTL). Two genome-wide strongly associated SNPs were detected on chromosomes 2 and 3, located near FEC associated QTLs and immune-related genes: GALNT6, KLRK1, KLRD1, CLEC1B, FGF13, TMEM52B, OLR1, and CLEC7A. The identified genes are involved in key defense mechanisms such as mucus synthesis, immune signaling, and natural-killer cell activation, supporting their relevance as candidate genes for GIN-resistance selection in Pelibuey hair-sheep.