Diagnosis of<unk>  is possible through lymphocyte cell counts, lymphocyte function tests, and genetic testing. A healthy immune system should contain large amounts of lymphocytes, but individuals with<unk>  will contain unusually small amounts of T-cells, non-functional B-cells, and some natural killer cells. Cell type Normal lymphocyte count average (range)<unk>  count average (range) T-cells 3,680 (2,500–5,500) 200 (0-800) B-cells 730 (300–2,000) 1,300 (44 - >3,000) NK cells 420 (170–1,100) <100 Total 0–3 months: 5,400 (3,400–7,300) <2,000 Individuals with<unk>  often have decreased lymphocyte function. This can be tested through the introduction of agents to the immune system; the reaction of the lymphocytes is then observed. In<unk> , Antibody responses to introduced vaccines and infections are absent, and T-cell responses to mitogens, substances that stimulate lymphocyte transformation, are deficient. IgA and IgM immunoglobulins, substances that aid in fighting off infections, are very low. The absence of a thymic shadow on chest X-rays is also indicative of<unk> . In a normal child, a distinctive sailboat shaped shadow near the heart can be seen. The thymus gland in normal patients will gradually decrease in size because the need for the thymus gland diminishes. The decrease in the size of the thymus gland occurs because the body already has a sufficient number of developed T-cells. However, a patient with<unk>  will be born with an abnormally small thymus gland at birth. This indicates that the function of thymus gland, of forming developed T-cells, has been impaired. Since the mutation in<unk>  is X-linked, there are genetic tests for detecting carriers in<unk>  pedigrees. One method is to look for family-specific IL2RG mutations. Finally, if none of those options are available, there is an unusual pattern of nonrandom X-chromosome inactivation on lymphocytes in carriers, thus looking for such inactivation would prove useful. If a mother is pregnant and the family has a known history of immunodeficiency, then doctors may perform diagnostic assessment in-utero. Chorionic Villus Sampling, which involves sampling of the placental tissue using a catheter inserted through the cervix, can be performed 8 to 10 weeks into gestation. Alternatively, Amniocentesis, which entails extracting a sample of the fluid which surrounds the fetus, can be performed 15 to 20 weeks into gestation. Early detection of<unk>  (and other types of<unk>  is also made possible through detection of T-cell recombination excision circles, or TRECs. TRECs are composed of excised DNA fragments which are generated during normal splicing of T-cell surface antigen receptors and T-cell maturation. This maturation process is absent across all<unk>  variants, as evidenced by the low counts of T-lymphocytes. The assay is performed using dried blood from a Guthrie card, from which DNA is extracted. Quantitative PCR is then performed and the number of TRECs determined. Individuals who have the<unk>  phenotype will have TREC counts as low as <30, compared to approximately 1020 for a healthy infant. A low TREC count indicates that there is insufficient development of T-cells in the thymus gland. This technique can predict<unk>  even when lymphocyte counts are within the normal range. Newborn screening of<unk>  based on TREC count in dried blood samples has recently been introduced in<unk> l states in the United States including California, Colorado, Connecticut, Delaware, Florida, Massachusetts, Michigan, Minnesota, Mississippi, New York, Texas, and Wisconsin. In addition, pilot trials are being performed in<unk> l other states beginning in 2013.
X-linked severe combined immunodeficiency
Severe combined immunodeficiency
Common variable immunodeficiency
X-linked agammaglobulinemia
Combined immunodeficiencies
Adult-onset immunodeficiency syndrome
Primary immunodeficiency
Chronic granulomatous disease