The characteristics of PIDs patients with the SD phenotype (Table 1) including micro-thrombocytopenia, recurrent sinopulmonary infections, hypogammaglobulinemia, catalase-positive pathogens, opportunistic infections, and lymphopenia were recognized as Wiskott-Aldrich syndrome (WAS), X-linked agammaglobulinemia (XLA), X-linked hyper IgM syndrome (HIGM), common variable immunodeficiency (CVID), chronic granulomatous disease (CGD), severe combined T- and B-cell immunodeficiency (SCID), according to the genetic mutations of the updated PIDs classification37, 38. Here, CAT is linked to severe combined immunodeficiency.