selective IgG subclass deficiency https://github.com/monarch-initiative/mondo/issues/9285 https://www.malacards.org/card/selective_igg_deficiency_disease NCIT:C27024 MEDGEN:56446 ICD9:279.03 selective Immunoglobulin G subclass deficiency DOID:14176 SCTID:190981001 MESH:D017099 UMLS:C0162539 GARD:0023033 MONDO:0001901 A classification of dysgammaglobulinemias characterized by low or undetectable serum levels of one of the four immunoglobulin class G (IgG) subclasses. Selective IgG1 deficiency is rare and primarily decreases the immune response to bacterial protein antigens. Selective IgG2 deficiency is the most common subclass deficiency among children and primarily leads to an inadequate response to bacterial polysaccharide antigens. Selective IgG3 deficiency is the most common subclass deficiency among adults and also primarily lowers the response to bacterial proteins. Selective IgG4 deficiency may be a clinically insignificant developmental variant, as IgG4 is a subclass that is virtually undetectable until the end of the first decade of life. Low levels of any IgG subclass will reduce the immune system's effectiveness and thus the clinical presentation of these diseases is usually recurrent infection, particularly by encapsulated bacteria. immunoglobulin heavy chain deficiency selective IgG immunodeficiency