Selective immunoglobulin A deficiency
The selective immunoglobulin A deficiency (English Selective IgA deficiency; SIgAD ) is the most common human congenital immunodeficiency. It is characterized by the absence of a certain class of antibodies, the immunoglobulin A. Affected patients may be asymptomatic or suffer from a usually relatively mild accumulation of respiratory infections. A causal treatment is not available. A prominent patient was the artist Niki de Saint Phalle.
Causes
The exact cause of selective IgA deficiency is known only for a rare subtype. Most cases remain unexplained in this regard. They occur sporadically, only rarely is a familial aggregation was observed ( about 20 % of cases). The mode of inheritance can be autosomal dominant or autosomal recessive. The disease is associated with specific types of major histocompatibility complex on the short arm of chromosome 6 ( IGAD1 locus ).
Frequency and occurrence ( Epidemiology )
The frequency of selective IgA deficiency is reported in the literature with 1:160 to 1:18.500. Recent work suggests that the frequency lies in western industrialized countries at about 1:600 . This means that the prevalence is about 1 ‰ (more than every thousandth person is affected). In regions with a different genetic background, the frequency is often significantly lower ( eg in Japan with 1:18.500 ).
Hospital and symptoms
The clinical expression of the disease is highly variable. More than half of the patients are completely symptom free ( as in mucous membranes occurring IgG functions of the lack of IgA takes over ), about 30 % suffer from recurrent ( recurrent ) infections, particularly of the respiratory tract. Less common complaints relate to the digestive system, autoimmune diseases, allergies and cancer. The following associations in detail are:
- Infections (sinusitis, bronchitis, pneumonia )
- ( Diarrhea, partly due to infections with Giardia intestinalis ) Digestive Disorders
- Autoimmune Diseases ( Celiac Disease, lupus erythematosus, rheumatoid arthritis, Crohn's disease, ulcerative colitis)
- Allergies ( food allergies (particularly milk protein ), allergic bronchial asthma, atopy )
- Tumors ( lymphomas, thymomas, lung tumors, tumors of the digestive tract, especially stomach cancer)
Diagnosis
The diagnosis is made by repeated determination of the concentration of immunoglobulin A (IgA ) in the blood serum. In patients with selective IgA deficiency, IgA is typically undetectable or greatly reduced (near the lower detection limit, always <0.3 g / l). Mostly, both subclasses ( IgA1 and IgA2 ) are affected. IgG and IgM are normal. Other immunodeficiencies (see differential diagnosis) and secondary IgA deficiency by medication or under other conditions must be excluded.
- IgG Subklassendefekte ( can also kombininert occur with IgA deficiency)
- Variable immunodeficiencies ( common variable immunodefiencies, CVID can also be combined with IgA deficiency occur )
- Secondary immunodeficiencies with IgA deficiency (eg due to multiple myeloma or by drugs )
- Ataxia Telangiectasia
Therapy
A faceted the cause of the disease treatment does not exist. Patients who are symptom-free, require no therapy, which represents the majority of all patients. If there is any infection, they must be dealt with in each case corresponding to the site of infection and pathogen, such as antibiotics. In some patients, a prophylactic therapy with antibiotics is required. Treatment with intravenous infusion of immunoglobulin (IVIG for intravenous immunoglobulin ) is usually not be considered, as this in patients with selective IgA deficiency IgA antibodies to be formed, which can then lead to severe allergic reactions (IgA is the body hitherto "unknown", which is why a defensive reaction initiated ). The selective IgA deficiency thus represents the most important contraindication to IVIG therapy dar. In blood transfusions, it may by this mechanism also result in allergic reactions, if the recipient suffers from selective IgA deficiency. This is also the reason, it is recommended in the patients with selective IgA deficiency to carry an emergency card with you and to make attending physicians on the diagnosis of attention.
Forecast
The life expectancy of patients with selective IgA deficiency is normal or only slightly reduced in the rule. The prognosis is so much better than all other congenital immunodeficiencies.