Distribution of validated genetic modifiers. A. Protein function of modifiers, as annotated on flybase.org, grouped into major categories. Stj, rasp, slmb, Rpl41/NaCP60E, and punch were included in two categories. B. Modifier loci categorized according to mutant phenotypes (when available). FKBP59, Cact, Scramb1, and Stj were associated with two phenotypic categories.