B cell deficiency agammaglobulinemia ICD9:279.00 A decreased level of serum immunoglobulins. It may be inherited or acquired. It is caused by decreased or inefficient production of immunoglobulins from B cells or by a decrease in the numbers of B cells themselves. Low levels of immunoglobulins will affect the immune system's ability to combat bacterial infection. Supplementation of immunoglobulins is needed to prevent worsening outcomes. GARD:0020320 Orphanet:183669 MEDGEN:168 MONDO:0015977 DOID:2583 OMIMPS:601495 Gammaglobulin Deficiency antibody Deficiency agammaglobulinemia Immunoglobulin Deficiency MESH:D000361 MedDRA:10001471 UMLS:C0001768