Early diagnosis of<unk>  is usually difficult due to the need for advanced screening techniques. Several symptoms may indicate a possibility of<unk>  in a child, such as a family history of infant death, chronic coughs, hyperinflated lungs, and persistent infections. A full blood lymphocyte count is often considered a reliable manner of diagnosing<unk> , but higher lymphocyte counts in childhood may influence results. Clinical diagnosis based on genetic defects is also a possible diagnostic procedure that has been implemented in the UK. Some<unk>  can be detected by sequencing fetal DNA if a known history of the disease exists. Otherwise,<unk>  is not diagnosed until about six months of age, usually indicated by recurrent infections. The delay in detection is because newborns carry their mother's antibodies for the first few weeks of life and<unk>  babies look normal. Newborn screening Several countries test all newborns for<unk>  as a part of routine newborn screening. All states in the U.S. are performing screening for<unk>  in newborns using real-time quantitative PCR to measure the concentration of T-cell receptor excision circles. United Kingdom intends to introduce newborn screening for<unk>  in September 2021.
Severe combined immunodeficiency
Common variable immunodeficiency
X-linked severe combined immunodeficiency
X-linked agammaglobulinemia
Primary immunodeficiency
Combined immunodeficiencies
Chronic granulomatous disease
Adult-onset immunodeficiency syndrome