TYK2 and systemic lupus erythematosus: Mice deficient in the orthologs of four of the nine putative disease genes (44.4%) at the ancestry-heterogeneous loci for SLE, Tnfrsf13b-, Ikzf1-, Prkcb-, and Tyk2-demonstrated abnormal IgG levels40 (MP:0020174), while at putative ancestry-heterogeneous loci (4/22 or 18.2%; OR = 3.43, Fisher exact test P = 0.185) or ancestry-shared loci (14/120 or 11.6%; OR = 5.92, Fisher exact test P = 0.027), proportionately fewer genes caused aberrant IgG levels in mice.