As a model for NBS, the approach published online in January in the Annals of Neurology provides evidence that this approach could be implemented if approved by regulatory bodies at a state level or alternatively through the Secretary’s Advisory Committee on Heritable Disorders in Newborns and Children.
“The three-step model is poorly adapted to newborn screening in the USA,” said Jerry R. Mendell, MD, principal investigator of the study and current director of the Center for Gene Therapy at The Research Institute at Nationwide Children’s Hospital. “It can work efficiently in a publically-funded health care system where newborn care is designated at specific times post-delivery making follow-up blood draws a realistic part of the total program for child welfare.” In the USA, mother and child are discharged within 24 to 48 hours following uncomplicated deliveries and post-natal care cannot be enforced. Thus, many newborns with elevated CKs at birth would be lost to follow up.
The two-tier system developed by Dr. Mendell permits heel blood taken at birth to be tested initially for CK with follow up DNA testing for DMD. A CK is obtained on the dried blood spot and if the level exceeds a predetermined threshold, DNA testing is automatically done from the same sample. No follow up blood samples are required. “This two-tier system (CK and DNA testing on same sample) is practical, comprehensive, and cost effective,” said Dr. Mendell, who is also a faculty member in The Ohio State University College of Medicine.
Promising new DMD therapies have rekindled interest in establishing a pathway for newborn screening in the DMD patient population. In 2004, Center for Disease Control workshop participants concluded that early diagnosis of DMD could have potential advantages for families, considering multiple treatment strategies were on the horizon. Funds were made available to Dr. Mendell and his team at Nationwide Children’s Hospital to explore the feasibility for establishing a model for DMD newborn screening in the United States.
The study appearing in Annals of Neurology documents a nearly-four-year pilot study of a voluntary DMD newborn screening program in Ohio. Over the course of the study, 37,749 newborn boys were screened and six were discovered to have DMD gene mutations. In cases where CK was elevated and DMD mutations were not found, the investigators extended the study to identify limb-girdle muscular dystrophy (LGMD) gene mutations as part of the screening process. The published study results confirmed that this was possible and reported that three of the cases had gene mutations found in LGMD.
“The program we have introduced differs from past programs and the current Antwerp approach to newborn screening for DMD that require a three-step process,” said Dr. Mendell. “This new process fits current U.S. obstetrics practices and allows us to readily distinguish false and true positive test results.”
Whether DMD treatment has advanced to the point of justifying newborn screening is a judgment yet to be made by state and federal agencies. “If and when an early therapy that improves the health outcome for individuals with DMD becomes available, our study serves as a model for implementation of newborn screening for DMD,” said Dr. Mendell.
In September 2012, the MDA will sponsor a workshop on newborn screening for DMD that will be co-chaired by Dr. Mendell and Michele Lloyd-Puryear from the National Institute of Child Health and Development, National Institutes of Health.
Dr. Mendell is the study’s co-corresponding author along with Robert B. Weiss, PhD, Department of Human Genetics at the University of Utah.
Erin Pope | Newswise Science News
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