Newborn Screening for Severe Combined Immune Deficiency with T Cell Receptor Excision Circle Assay in Mississippi 2012 – 2014

Rationale:  Severe combined immunodeficiency (SCID) is a life-threatening genetic disorder with severe deficiency of T-cells. SCID patients have severe viral, fungal and bacterial infections early in life, and is fatal by 1-2 years of life if not treated. Hematopoietic stem cell transplantation is most successful for SCID prior to 3.5 months of age. Early detection and treatment of SCID is imperative to prevent mortality.

Methods:  The state of MS began newborn screening (NBS) for SCID on all newborns in January 2012. Standard heel-stick blood Guthrie cards are used to measure T cell receptor excision circles (TRECs) by real-time polymerase chain reaction (PCR). Real time quantitative PCR assay for human beta actin gene was also used to monitor the integrity of the sample and the success of DNA extraction. All patients with presumptive positive screens were sent for immunologic testing. We report the results for the first 3 years of SCID screening in MS.

Results:  In 2012, 37,613 newborns were screened for SCID; 4 had presumptive positive screens, and 1 had SCID.  In 2013, 38,696 newborns were screened for SCID; 7 screens were presumptive positive, and 1 patient had SCID.  For 2014, 37,828 infants were screened for SCID; 7 had presumptive positive screens, and 2 (fraternal twins) had SCID. The present incidence of SCID in Mississippi is approximately 1 out of 28,500. 

Conclusions:  With NBS, we now know the incidence of SCID is more common than previously reported. Incidence of SCID in MS is higher than the national average of 1:58,000 found by newborn screening.