Severe combined immunodeficiency (SCID) is rare, but a founder mutation in the DNA repair enzyme Artemis (DCLRE1C) causes SCID in 1/2000 Navajo Native American infants. SCID infants lack T and B lymphocytes, and untreated SCID patients succumb to viral, bacterial and fungal infections early in life unless treated, usually by bone marrow transplant.
In 2005, Jennifer Puck, MD, developed a newborn screening (NBS) test for SCID based on measuring T-cell receptor excision circles (TRECs) in DNA isolated from infant dried blood spots. This test allows SCID to be detected in pre-symptomatic newborns, making possible optimal treatment. California started universal SCID NBS in 2010.
In a 2014 study of SCID NBS in 11 public health programs, Dr. Puck and her colleagues showed that SCID in the general population is twice as common as previously thought (1/58,000 births); 52 cases were found and none were missed; and the TREC assay also detected other disorders with low lymphocytes. 36 states and the Navajo Nation now have SCID NBS, and UCSF has treated 28 infants, including 5 Navajos referred here for bone marrow transplants. Dr. Puck directs the UCSF Jeffrey Modell Diagnostic Center for Primary Immunodeficiences and with Dr. Mort Cowan is developing gene therapy for Artemis deficient SCID.