MGI:104798Mutations at this locus primarily affect the immune system, causing increased susceptibility to infection, failure to form splenic B-cell follicles, increased inflammation and impaired contact hypersensitivity. Homozygotes also may show metabolic defects. Combined deletions of certain regulatory regions in the 3' UTR are embryonic lethal (homozygous) or cause arthritis and intestinal and cardiac valve inflammation and reduced lifespan (heterozygous).