<unk>  immunoglobulin A (IgA) deficiency (SIgAD) is a genetic immunodeficiency, a type of hypogammaglobulinemia. People with this deficiency lack immunoglobulin A (IgA), a type of antibody that protects against infections of the mucous membranes lining the mouth, airways, and digestive tract. It is defined as an undetectable serum IgA level in the presence of normal serum levels of IgG and IgM, in persons older than 4 years. It is the most common of the primary antibody deficiencies. Most such persons remain healthy throughout their lives and are never diagnosed.
Selective immunoglobulin A deficiency
Isolated primary immunoglobulin M deficiency
Primary immunodeficiency
IgG deficiency
X-linked agammaglobulinemia
Transient hypogammaglobulinemia of infancy
Chronic granulomatous disease
Combined immunodeficiencies