Severe Combined Immunodeficiency (SCID) is a group of disorders caused by defects in genes involved in the development and function of T-cells and other infection-fighting immune cells.

Newborns with SCID appear normal at birth, but typically develop life-threatening infections within a few months and without early intervention and treatment, death can occur within the baby's first year so early detection and treatment can markedly improve survival.

The first screening test has now been permitted to be marketed by the US Food and Drug Administration (FDA; Silver Springs MD, USA) for Severe Combined Immunodeficiency (SCID) in newborns. A few drops of blood taken from the newborn's heel, which is dried on filter paper, the test can determine whether a certain type of DNA, known as T-cell receptor excision circles (TREC DNA), is low or missing from the newborn's blood. Newborns with SCID typically have zero or low amounts of TREC DNA compared to healthy infants. Additional testing is required to obtain a SCID diagnosis.

The FDA reviewed the test through its de novo classification process, a regulatory pathway for some novel low- to moderate-risk medical devices that are not substantially equivalent to an already legally marketed device. The review included a clinical study of approximately 6,400 blood spot specimens from routine screening of newborns, 17 of which had confirmed SCID diagnosis. The EnLite Neonatal TREC Kit (PerkinElmer; Waltham, MA, USA) correctly identified all 17 SCID cases. The agency also evaluated the test's ability to accurately distinguish low TREC DNA numbers that would be observed in newborns with SCID, from high TREC DNA numbers that would be present in healthy newborns. The FDA found that the EnLite Neonatal TREC Kit could adequately detect very low TREC DNA values that are associated with SCID.

Alberto Gutierrez, PhD, director of the Office of In Vitro Diagnostics and Radiological Health at the FDA, said, “SCID is a fatal disease that can be treated with early intervention, including screening. For the first time, the FDA is allowing the marketing of a newborn screening test that will enable states to incorporate an FDA reviewed SCID test into their standard newborn screening panels and allow earlier identification for affected individuals.” The EnLite Neonatal TREC Kit is not intended for use as a diagnostic test or to screen for SCID-like syndromes, such as DiGeorge Syndrome or Omenn Syndrome. It is also not intended to screen for less acute SCID syndromes, such as leaky-SCID or variant SCID.

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US Food and Drug Administration 
PerkinElmer