Clinical and immunological phenotypes in DEF6-mutated patients include T-cell lymphopenia, low class-switched B cells, hepatosplenomegaly, autoimmune hemolytic anemia and bowel inflammation, all of which are reminiscent of CTLA-4 haploinsufficiency and LRBA deficiency13–18,48–50. Here, DEF6 is linked to autoimmune hemolytic anemia.