SCID Newborn Screening

What is SCID?

Severe Combined Immunodeficiency (SCID) leads to life-threating infections unless the immune system can be restored through a transplant, enzyme replacement or gene therapy. Early detection of SCID through screening of all newborns can make possible life-saving intervention before infections occur.

Newborn Screening for SCID is currently only done in six provinces in Canada: Ontario (since 2014),  Nova Scotia, New Brunswick and PEI (2016), Alberta and most recently Manitoba in May (2020). Quebec’s provincial application for SCID in the newborn screening program is currently under consideration, but the decision has been delayed due to COVID-19. CIPO continues to work with our National and Provincial partners to advocate for Newborn Screening for SCID across Canada.


In 2020, CIPO starting working with immunologists and families in BC to advocate for SCID to be added to the BC provincial newborn screening program. We need YOUR help! You can help by:

  • Writing a letter to your MLA
  • Asking for a meeting with your MLA
  • Writing to the Minister of Health

CIPO can assist with letter templates, meeting preparation and any supporting documents you need. If you would like to get involved, please email 

TREC Testing

Population based newborn screening happens on a large scale, a blood spot from a newborn heel is dried and used to test for a multitude of diseases that vary in every province.

T-cells are approximately 70% of lymphocytes in healthy infants, and the absence of T-cells causes the total lymphocyte count of most infants with SCID to be low. However, T-cells alone would not capture all SCID patients.

Therefore, the TREC test was developed. TREC (T-cell Receptor Excision Circles) are circular DNA molecules formed within the T-cells developing in the thymus. Normal infants have 1 TREC per 10 T-cells. Infants with SCID, lack TREC altogether.

Not all T-cell deficiency diseases are detected by the TREC test, as some deficiencies have patients born with normal TREC levels (NEMO for example).