Primary Immunodeficiency Diseases (PID) are a group of primarily single-gene disorders of the immune system.
Primary denotes the genetic nature of the defects, differentiating them from secondary or acquired immunodeficiencies caused by malnutrition, infection, chemotherapy, or other external
agents.
The defining characteristics of primary immunodeficiency diseases make them candidates for a public health intervention approach.
Although the clinical manifestations and underlying genetic defects are diverse, primary immunodeficiency diseases share the common feature of increased susceptibility to infection and collectively result in substantial morbidity and shortened life spans.
However prompt diagnosis and treatment can be lifesaving and may result in marked improvements in the quality and length of life.
The heterogeneity of primary immunodeficiency diseases and the limited understanding of the relation between genotype and phenotype also hinder intervention efforts.
Additional obstacles include the difficulty of diagnosis in the absence of a high index of suspicion and the lack of awareness of health care providers and the public which impedes the timely recognition of affected person by using a combination of clinical suspicion and diagnostic testing.