The symptoms of<unk>  vary between people affected. Its main features are hypogammaglobulinemia and recurrent infections. Hypogammaglobulinemia manifests as a significant decrease in the levels of IgG antibodies, usually alongside IgA antibodies; IgM antibody levels are also decreased in about half of people. Infections are a direct result of the low antibody levels in the circulation, which do not adequately protect them against pathogens. The microorganisms that most frequently cause infections in<unk>  are bacteria Haemophilus influenzae, Streptococcus pneumoniae, and Staphylococcus aureus. Pathogens less often isolated from people include Neisseria meningitidis, Pseudomonas aeruginosa, and Giardia lamblia. Infections mostly affect the respiratory tract (nose, sinuses, bronchi, lungs) and the ears; they can also occur at other sites, such as the eyes, skin, and gastrointestinal tract. These infections respond to antibiotics but can recur upon discontinuation of antibiotics. Bronchiectasis can develop when severe, recurrent pulmonary infections are left untreated. In addition to infections, people with<unk>  can develop complications. These include: * autoimmune manifestations, e.g. pernicious anemia, autoimmune haemolytic anemia (AHA), idiopathic thrombocytopenic purpura (ITP), psoriasis, vitiligo, rheumatoid arthritis, primary hypothyroidism, atrophic gastritis. Autoimmunity is the main type of complication in people with<unk> , appearing in some form in up to 50% of individuals; * malignancies, particularly non-Hodgkin's lymphoma and gastric carcinoma; * enteropathy, which manifests with a blunting of intestinal villi and inflammation, and is usually accompanied by symptoms such as abdominal cramps, diarrhea, constipation, and, in some cases, malabsorption and weight loss. Symptoms of<unk>  enteropathy are similar to those of celiac disease, but do not respond to a gluten-free diet. Infectious causes must be excluded before a diagnosis of enteropathy can be made, as people with<unk>  are more susceptible to intestinal infections, e.g. by Giardia lamblia; * lymphocytic infiltration of tissues, which can cause enlargement of lymph nodes (lymphadenopathy), of the spleen (splenomegaly) and of the liver (hepatomegaly), as well as the formation of granulomas. In the lung this is known as granulomatous–lymphocytic interstitial lung disease. Anxiety and depression can occur as a result of dealing with the other symptoms.<unk>  patients generally complain of severe fatigue. As with any antibody deficiency, the most<unk>  types of infections and illnesses involve the ears, sinuses, nose, and lungs.<unk>  infections include: * Pneumonia * Ear Infections * Sinusitis * Chronic coughing (lasting from a few weeks to many months) * Gastrointestinal Infections Gastrovascular infections, such as infections or inflammation are very<unk> , in most cases. Many signs of a gastrovascular infection include abdominal pain, nausea, bloating, vomiting, diarrhea, and weight loss. Many individuals have an impaired ability to absorb nutrients, including vitamins, proteins, minerals, fats, and sugar within the digestive tract. Due to changes in development in B cells, some individuals with<unk>  have accumulations of lymphocytes in lymphoid tissues. This can cause mild to severely swollen lymph nodes or inflammation of the spleen. In addition, a certain percentage of individuals with<unk>  are more susceptible to developing certain forms of cancer, more so than those without<unk> . The two most<unk>  cancers in<unk>  patients include lymphoma and certain stomach cancers. The risk for these given cancers is almost fifty times greater in<unk>  patients than those without. Onset symptoms, including frequent infections, may occur during adolescence, however, for many patients, the symptoms and diagnosis may not occur until adulthood. People with<unk>  have trouble fighting off infections due to the lack of antibodies produced which normally resit invading microbes. Due to impaired antibody development vaccines are not effective. Recurring bacterial infections are generally found in the upper and lower areas of the respiratory tract. Many who have a recurring lung infection, report developing, chronic lung diseases, and potentially life-threatening complications later in life.
Common variable immunodeficiency
Severe combined immunodeficiency
X-linked severe combined immunodeficiency
X-linked agammaglobulinemia
Chronic granulomatous disease
Primary immunodeficiency
Wiskott–Aldrich syndrome
Combined immunodeficiencies