Selective 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. Signs and symptoms
85–90% of IgA-deficient individuals are asymptomatic, although the reason for lack of symptoms is relatively unknown and continues to be a topic of interest and controversy. Some patients with IgA deficiency have a tendency to develop recurrent sinopulmonary infections, gastrointestinal infections and disorders, allergies, autoimmune conditions, and malignancies. These infections are generally mild and would not usually lead to an in-depth workup except when unusually frequent. They rarely present with severe reactions, including anaphylaxis, to blood transfusions or intravenous immunoglobulin due to the presence of IgA in these blood products. Patients have an increased susceptibility to pneumonia and recurrent episodes of other respiratory infections and a higher risk of developing autoimmune diseases in middle age.IgA deficiency and common variable immunodeficiency (CVID) feature similar B cell differentiation arrests, but it does not present the same lymphocyte subpopulation abnormalities. IgA-deficient patients may progress to panhypogammaglobulinemia characteristic of CVID. Selective IgA and CVID are found in the same family.
Uridine triacetate (INN), formerly known as vistonuridine, is an orally active tri-acetylated prodrug of uridine used:

in the treatment of hereditary orotic aciduria (brand name Xuriden  ZOOR-ə-den);
to treat people following an overdose of chemotherapy drugs 5-fluorouracil (5-FU) or capecitabine regardless of the presence of symptoms, or who exhibit early-onset, severe or life-threatening toxicity affecting the cardiac or central nervous system, and/or early-onset, unusually severe adverse reactions (e.g., gastrointestinal toxicity and/or neutropenia) within 96 hours following the end of fluorouracil or capecitabine administration (brand name Vistogard).Uridine triacetate was developed, manufactured and distributed by Wellstat Therapeutics. It was granted breakthrough therapy designation by the U.S. Food and Drug Administration (FDA) and approved for use in the United States in 2015. References
External links
"Uridine triacetate". Drug Information Portal. U.S. National Library of Medicine.