Pediatric selective immunoglobulin A deficiency

Introduction to selective immunoglobulin A deficiency in children Selective immunoglobulin A deficiency (SIgAD) is the most common PID and is a humoral immunodeficiency disease. basic knowledge The proportion of illness: 0.005% Susceptible people: children Mode of infection: non-infectious Complications: lupus erythematosus dermatomyositis mixed connective tissue disease idiopathic thrombocytopenic purpura ulcerative colitis atrophic gastritis gastric ulcer hepatitis

The cause of selective immunoglobulin A deficiency in children

(1) Causes of the disease

The cause is still unclear. Most people think that this disease is a group of syndromes caused by multiple causes. In addition to genetic factors, environmental factors are also important.

(two) pathogenesis

The pathogenesis of this disease is similar to that of common variant immunodeficiency disease (CVID), which can be autosomal recessive or autosomal dominant, or sporadic, MHC (human HLA) on chromosome 6 The polymorphisms of amino acids or epitopes in the DR, DQ and DP loci of HLAII are closely related to the disease, and are also associated with MHCIII C4A or 21 hydroxylase (CYP21) site mutations. IgA deficiency disease and 9 pairs of chromosomes on the PAX5 gene mutation may be related, but have not been confirmed, IgA1 or IgA2 subtype deficiency is due to the deletion of the immunoglobulin heavy chain gene of the 14th chromosome, in many cases, TH cell dysfunction, B cells It is not possible to synthesize IgA by the effective auxiliary stimulation signal provided by T cells, and it has been confirmed that the TGF-1 (TGF-1) secreted by T cells is one of the reasons.

Prevention of selective immunoglobulin A deficiency in children

The cause of the disease is still unclear. The current focus is on the prevention and treatment of genetic diseases, such as:

1. Screening for patient family members.

2. Genetic counseling, detection of carriers of disease-causing genes, and guidance on fertility.

3. Prenatal diagnosis, etc.

Pediatric selective immunoglobulin A deficiency complications Complications Lupus dermatomy dermatomyositis mixed connective tissue disease idiopathic thrombocytopenic purpura ulcerative colitis atrophic gastritis gastric ulcer hepatitis

Often associated with autoimmune diseases such as lupus erythematosus, dermatomyositis, rheumatoid arthritis, nodular arteritis, chronic thyroiditis, mixed connective tissue disease, autoimmune hemolytic anemia, and idiopathic thrombocytopenia Purpura, etc.; may be associated with allergic diseases, repeated infections, etc.; may have malabsorption, may be associated with nutritional diseases, may be associated with ulcerative colitis, segmental enteritis, atrophic gastritis, gastric ulcer, pancreatitis and hepatitis, etc. Can have mental retardation, epilepsy, may be associated with asthma or urticaria, infusion of blood containing IgA to sensitize the sick child, can have severe allergic reactions; may be associated with malignant tumors.

Pediatric selective immunoglobulin A deficiency symptoms common symptoms repeated infections gastrointestinal symptoms diarrhea immune dysfunction shock

The lightest person can have no symptoms for a long time. Many patients only show mild upper respiratory tract infections, and some patients have various associated diseases, especially autoimmune diseases, allergic diseases, repeated infections, etc., diagnosed at age from 6 months. 12 years old, compared with foreign countries, the incidence of nervous system diseases, autoimmune diseases and allergic diseases is relatively rare, while respiratory infections and intestinal diseases are more common.

Symptoms of respiratory infection may begin in infancy, some patients may continue to puberty, and then relieved, and some patients begin to develop symptoms in adulthood, and may even be delayed until 50 to 60 years of age.

Some cases have gastrointestinal symptoms, such as diarrhea and malabsorption. Small intestinal biopsy can find almost all IgM plasma cells in the lamina propria, but lack IgA plasma cells, this disease may be associated with ulcerative colitis, segmental enteritis , atrophic gastritis, gastric ulcer, intestinal lymphatic dilatation, intestinal giardia infection, pancreatitis and hepatitis.

About 50% of cases are associated with autoimmune disease, chronic active hepatitis, systemic lupus erythematosus, dermatomyositis, rheumatoid arthritis, nodular arteritis, chronic thyroiditis, mixed connective tissue disease, idiopathic Adrenal insufficiency, autoimmune hemolytic anemia, and idiopathic thrombocytopenic purpura, common autoimmune phenomena (only autoantibodies, asymptomatic), including anti-IgA antibodies, anti-IgG antibodies, anti-IgM antibodies , anti-thyroglobulin antibody, rheumatoid factor, anti-nuclear antibody, anti-deoxyriboprotein antibody, anti-smooth muscle antibody, anti-mitochondrial antibody, anti-basement membrane antibody, anti-wall cell antibody and the like.

Some patients with mental retardation and sensory nerve abnormalities are also closely related to primary epilepsy, and may be associated with asthma or urticaria. About 10% of European and American asthma patients are selective IgA deficiency.

Infusion of IgA-containing plasma, whole blood or IVIG (containing trace amounts of IgA) can sensitize the sick child, producing high concentrations of anti-IgA antibodies. When re-injecting blood products containing IgA, serious allergic reactions, including allergies, can occur. Sexual shock, an allergic reaction may occur in those who have not had a history of infusion, which may be related to IgA sensitization caused by mother and child placental infusion and drinking milk.

Patients with selective IgA deficiency are sometimes associated with malignant tumors such as lung cancer, stomach cancer, colon cancer, rectal cancer, breast cancer, ovarian cancer, uterine cancer, thymoma, leukemia and lymphoma.

Examination of selective immunoglobulin A deficiency in children

The serum IgA level of patients is often less than 0.05g/L, or even completely undetectable. Secretory IgA is not detected in the saliva of severely ill children, the urine content is extremely low, and the IgG and IgM levels are normal or elevated, or even 2 More than normal, about 40% of children can detect autoantibodies.

According to the choice of the disease, such as chest X-ray examination when the lung infection; gastritis, gastric ulcer and barium meal examination; epilepsy to do EEG examination and so on.

Diagnosis and identification of selective immunoglobulin A deficiency in children

diagnosis

The diagnostic criteria for Stiehm are used in the diagnosis of this disease:

1 serum IgA content <50mg / L;

2 serum IgG, IgM levels are normal or elevated;

3 cell immune function is normal or reduced;

4 Excluding other causes of serum IgA is low, but the diagnosis should pay attention to the development of IgA system is closely related to age, infants within 1 year old, especially <6 months infant serum IgA is in a state of deficiency, and SIgAD has a natural recovery tendency, so The diagnosis of SIgAD should be cautious. In addition, the general serum IgA level can indirectly reflect the status of SIgA, but the serum IgA of individual patients is normal, but there is a lack of secretory components, so patients suspected of SIgAD should be tested for SIgA of saliva to exclude secretory components. lack of.

Differential diagnosis

Immunodeficiency diseases are characterized by repeated infections, and can occur in uncommon serious infections, persistent infections, poor therapeutic effects, etc., humoral immunodeficiency is more common in Gram-positive infections, and cellular immunodeficiency is more common in Gram Negative bacteria, fungi, protozoa, viruses, mycobacteria, etc.; X-ray examination in the absence of thymus in infancy suggests cellular immunodeficiency or combined immunodeficiency, this disease is a humoral immunodeficiency disease, should pay attention to other humoral immunodeficiency diseases Identification, such as congenital hypogammaglobulinemia, infants with temporary hypogammaglobulinemia and selective IgM deficiency, serum IgA quantitative determination, IgA <0.05g / L suggest IgA deficiency, while SIgA Lack, while other Ig is normal; clinical manifestations are milder than other humoral immunodeficiency diseases, some patients may be asymptomatic; repeated respiratory or gastrointestinal infections in infancy, often accompanied by allergic diseases or autoimmune diseases; other body fluids Immunodeficiency diseases generally have a serious prognosis and are prone to early death in children.

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