States should offer newborn severe combined immunodeficiency screening, urges national advisory committee

There are now 5 states (California, Louisiana, Massachusetts, New York, and Wisconsin) that at least offer newborn screening for severe combined immunodeficiency (SCID), according to the National Newborn Screening and Genetics Resource Center.

Work is going on apace to convince other states to adopt the testing, even as research is done on how the tests and follow-up work are doing, according to reports at the national Advisory Committee on Heritable Diseases in Newborns and Children January meeting in Washington.

SCID was added to the national Recommended Uniform Screening Panel for newborns by the Department of Health and Human Services last year, with related T-cell lymphocyte deficiencies added to the list of secondary targets for the testing.

Newborns with SCID develop severe, often opportunistic, infections that lead to early death. Studies indicate that treatment, most commonly with hematopoietic stem cell transplant, is effective in decreasing both morbidity and mortality.

There is also evidence from early detection in siblings of children with SCID that earlier treatment may be more effective, said that report.

All states now doing the SCID screening are using a TREC (T-cell excision circles) assay, said Carla Cuthbert, PhD, head of the Centers for Disease Control and Prevention's Newborn Screening and Molecular Biology Branch.

That test, according to the Wisconsin newborn screening program, is based on the measurement of DNA fragments that are byproducts of the production of normally functioning T-cells. A baby with SCID does not produce normal T-cells and will not have detectable TRECs.

Of several states that have public and private funding to study how the testing is working, Wisconsin has tested about 206,000 babies since it began several years ago, said Cuthbert. With the algorithm used in that state, about 160 babies had abnormal results.

Final results found 5 patients with severe lymphopenia, including 2 SCIDs cases. There have been successful bone marrow transplants in some, and other treatments still planned for others.

R. Rodney Howell, MD, chair of the heritable disorders committee, told the meeting that the committee had originally recommended that there be experience in SCID testing in many babies before it is done all over the United States. Funding from the National Institutes of Health and other sources is allowing that to happen. When those pilot data are available from state labs, the information will help other states adopt the recommendation.

Marcia Boyle, head of the advocacy group Immune Deficiency Foundation, told the committee that a big challenge to implementation in states is funding, with cost estimates for developing the infrastructure for SCID screening ranging from $500,000 to $1 million per state.

In some cases, she said, the foundation is told that it must wait its turn behind other disease groups wanting attention.

Along those lines, states need to develop strategies, including Medicaid policies, to give patients access to specialists, including sometimes sending them to out-of-state medical centers with bone marrow transplant expertise, said Boyle.