Although newborn TREC testing is most commonly used to detect SCID, other clinical applications exist, such as guiding the avoidance of live viral vaccinations in certain cases. For instance, administration of the rotavirus vaccine in patients with inadequate T-cell immunity can lead to severe diarrheal disease; such insufficiencies can be detected using the TREC assay.

From 2010 to 2017, the program screened over 3.25 million infants for SCID and other T-cell abnormalities. Infants with SCID and T-cell lymphopenia were positively detected at a rate of 1 in 65,000 and 1 in 15,300 births, respectively. With respect to efficacy, early treatment of infants with SCID resulted in a survival rate of 94%. Numerous infants with non-SCID disorders were also diagnosed and successfully treated.

The researchers noted that the incidence of both SCID and non-SCID T-cell lymphopenia were higher and more genetically diverse than initially understood.

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Clinical Recommendations and Raising Awareness

Allogeneic hematopoietic stem cell transplantation is the treatment of choice for infants with SCID. The procedure involves finding an acceptable matched donor, and optimal outcomes are typically seen if treatment is started promptly in order to reduce the likelihood of life-threatening infections. Other treatment options, such as lymphocyte correction by gene therapy and enzyme replacement therapy, are used in rare cases. Some areas of future development include the design of novel targeted therapies and improved strategies to prevent cytomegalovirus infection.

“It is challenging to raise awareness about rare diseases,” Dr Puck told Hematology Advisor. “One important message [moving forward] would be the high value of population-based newborn screening for conditions that are treatable and [the] need [for] prompt [treatment] to save lives.”

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1. Amatuni GS, Currier RJ, Church JA, et al. Newborn Screening for Severe Combined Immunodeficiency and T-cell Lymphopenia in California, 2010-2017. Pediatrics. 2019;143(2):e20182300. doi: 10.1542/peds.2018-2300

2. Thakar MS, Hintermeyer MK, Gries MG, Routes JM, Verbsky JW. A Practical Approach to Newborn Screening for Severe Combined Immunodeficiency Using the T Cell Receptor Excision Circle Assay. Front Immunol. 2017;8:1470. doi: 10.3389/fimmu.2017.01470