IgG immunoglobulins are composed of four sub types named IgG1, IgG2, IgG3 and IgG4. Each subclass is present in the serum in different concentrations, varies with age, and has different roles for immune response. Abnormal levels of one or more subclasses may be associated with certain conditions: antibody deficiencies, cellular immunodeficiency’s, and innate immune disorders.
Because they are prevalent in varying serum concentrations, a deficiency may be masked when only measuring total IgG. Many patients with PI are undiagnosed, underdiagnosed, or misdiagnosed. Compared to 2013 in 2018 there has been a 57% increase the number of patients followed and identified with a PI defect in the United States.1
For this reason, the measurement of IgG subclass concentrations is important in the assessment of the immune system. Early diagnosis results in decreased morbidity and mortality and in lower costs, estimated to be annual savings to the health care system for each diagnosed patient of $85,882.1
One of the most common signs of primary immunodeficiency is having infections that are more frequent, longer lasting, or harder to treat than the infections of someone with a normal immune system. Also, PI patients may get infections that a person with a healthy immune system would not be likely to get (so called, “opportunistic infections”).
Clinical signs and symptoms differ depending on the type of primary immunodeficiency disorder and can vary from person to person.