Fatal Pneumocystis jirovecii and Cytomegalovirus Infections in an Infant With Normal TRECs Count: Pitfalls of Newborn Screening for Severe Combined Immunodeficiency.

Newborn screening for severe combined immunodeficiency using T-cell receptor excision circles allows prompt diagnosis and initiation of supportive and curative therapy thereby reducing morbidity and mortality. However, profound combined immunodeficiencies with normal numbers of nonfunctional T cells will go undetected. We present a patient with calcium release-activated calcium channel gene (ORAI1) deficiency and normal T-cell receptor excision circle numbers observed after diagnosis at the age of 14 months who suffered from disseminated fatal cytomegalovirus and Pneumocystis jirovecii infection, demonstrating a potential pitfall of the current newborn screening program.