PRF1 and infection: Along with linkage and genome-wide association evidence for a QTL mapping to the perforin gene region on LG14 (Tables 3, 4 and 5), these patterns suggest that differential expression of the perforin gene itself could play an important role in the immune defense of L. rohita against A. hydrophila infection, and that polymorphisms affecting the expression of this gene during the time course of infection could influence disease resistance.