A recurrent form of sinusitis.

An increased susceptibility to respiratory infections as manifested by a history of recurrent respiratory infections.

Inflammation of the conjunctiva.

Decreased levels of immunoglobulin A (IgA).

An abnormally decreased level of immunoglobulin M (IgM) in blood.

Increased susceptibility to otitis media, as manifested by recurrent episodes of otitis media.

Increased susceptibility to bacterial infections, as manifested by recurrent episodes of bacterial infection.

A group of phenotypically heterogeneous genetic disorders characterized by profound deficiencies of T- and B-cell function, which predispose the patients to both infectious and noninfectious complications.

A deviation from the normal count of T cells.

A deviation from the normal count of B cells, i.e., the cells that are formed in the bone marrow, migrate to the peripheral lymphatic system, and mature into plasma cells or memory cells.

A reduction in the normal proportion of class-switched memory B cells (CD19+/CD27+/IgM+/IgD+) relative to the total number of B cells. Marginal zone B cells undergo limited somatic hypermutation and produce high-affinity IgM and some IgG, whereas class-switched memory B cells synthetize IgG, IgM, and IgA.

A lasting reduction beneath the normal level of total immunoglobulin G (IgG) in the blood.

Level of isohemagglutinin reduced below expected concentration. An isohemagglutinin refers to the naturally occurring antibodies in the ABO blood group system (i.e., anti-A in a group B person, anti-B in a group A person, and anti-A, anti-B, and anti-A,B in a group O person).