why should trec and krec quantification assay be concerned to screen of newborns in developing countries?

Primary immunodeficiencies contain a set of several different diseases. giving the fact that their clinical outcome ranges from mild to potentially life-threatening, detecting the patients with these diseases in the neonatal period is considered as the main goal of efforts that are currently being made. it has been reported that t-cell receptor excision circles (trecs) and kappa-deleting recombination excision circles (krecs) are circular dna segments produced in t and b cells during their maturation in the thymus and bone marrow, respectively. fortunately, excision circles can be reliably quantified using real-time quantitative pcr techniques. the trec and krec assays, as introduced in the newborn screening program (nbs), allow early identification of the disease and may result in discovering new genetic defects including severe combined immunodeficiencies (scid), primary agammaglobulinaemias (such as xlinked agammaglobulinaemia), and inherited haemophagocytic syndromes (such as familial haemophagocytic lymphohistiocytosis). regarding, the cost-effectiveness, survival of children, and success in improving the life quality of children involved in newborn screenings for severe combined immunodeficiency has been demonstrated. here, we discuss about trec and krec assay, their applications, and also assessment of the cost effectiveness of an established program for newborn screening, in terms of trecs and krecs quantification in iran.