Regarding therapies, patients diagnosed with activated PI3K δ syndrome (APDS), cytotoxic T lymphocyte-associated antigen 4 (CTLA 4) deficiency received therapies specifically oriented in the mechanism of the underlying immunological disease; sirolimus for APDS and CTLA4-Ig (abatacept) for CTLA 4 deficiency. Here, CTLA4 is linked to Down syndrome.