Colored scanning electron micrograph (SEM) of a lymphocyte cell. Lymphocytes are divided into either B-cells or T-cells.
SCIDS Screening Now Required
issue 1 | winter 2012
Severe combined immune deficiency syndrome (SCIDS), the rare and devastating disease made famous by David Vetter ("the Bubble Boy"), can be diagnosed as part of the standard newborn screening. Michigan recently made SCIDS testing mandatory, since early diagnosis and treatment with bone marrow transplants have resulted in high survival rates.
"SCIDS is a heterogeneous group of disorders, but the common denominator is lack of T-cell and B-cell immunity," says Jim Connelly, M.D., U-M pediatric bone marrow transplant physician. "Without diagnosis or treatment, SCIDS has universal mortality before two years of life from overwhelming infection."
"The actual test in the newborn screening is the TREC assay (T-cell receptor excision circles)," explains Kelly Walkovich, M.D., a U-M pediatric hematologist/oncologist. "The absence of TRECs is characteristic of severe T-cell impairment and possible SCIDS."
SCIDS patients who undergo bone marrow transplant as early as possible have a significant survival advantage over patients transplanted later. Patients transplanted very early in life show survival rates around 90 percent.
A positive TREC assay is automatically rerun a second time with the same sample. A verified abnormal result triggers notification to the primary care physician, because additional testing requires flow cytometry and a CBC with differential, which take about 48 hours. If those tests are normal, no further testing is needed.
"Abnormal results require patient referral to a comprehensive pediatric center with expertise in managing immunodeficiency disorders and performing bone marrow transplants," explains Walkovich. "Mott Children's Hospital's immunohematology clinic is unique in that we offer patients direct and simultaneous access to hematologists, immunologists, infectious disease specialists, bone marrow transplant specialists and geneticists for thorough and expedited care for children with suspected immunodeficiencies."