Pediatric geneticist Piero Rinaldo, M.D., Ph.D., presented the findings at the annual meeting of the American Association for the Advancement of Science (AAAS) in Washington, D.C.
Dr. Rinaldo said that tandem mass spectrometry – a multiplex platform available to screen for upwards of 40 potentially life-threatening genetic diseases – is not in use in many states. The inconsistent use of existing technology at the state level means that children born in some states will not be diagnosed until it is too late, Dr. Rinaldo explained. In nearly all cases, immediate treatment for recognized genetic diseases can improve or cure infants' conditions. If undiagnosed in the first few days after birth, some conditions can kill or cause irreversible brain damage.
In addition to unresolved issues of lack of uniformity and fairness, Dr. Rinaldo addressed the problem of inconsistent performance at the analytical level leading to significant variability in quality parameters, for example false positive rate and positive predictive value. He argued that better performance could be achieved by the addition of second-tier analyses. These are biochemical and/or molecular confirmatory tests performed on the same blood spot collected at birth. The advantage of testing the specimen already available, instead of requesting a repeat collection or a blood sample, is to prevent the anxiety and stress that families would experience until the initial screening results on their infants are shown to be false.
Dr. Rinaldo told conference attendees that Mayo Clinic cooperated with the Minnesota Department of Health to develop a secondary analysis of the false positives that all but eliminated the problem for one particular condition, congenital adrenal hyperplasia. Compared to a relatively low false positive rate of just under half of one percent in 2003, the secondary screen lowered the false positive percentage to six-hundredths of one percent (0.06%) in the last half of 2004. He says the system not only improves the value of screenings, but can make them more cost effective.
He also reported that in the near future screening programs are likely to be further expanded to include testing beyond the newborn period for additional diseases such as Wilson's disease, which causes copper to build in vital organs such as the brain and liver, and congenital disorders of glycosylation, a fast growing group of newly discovered inborn errors of metabolism.
Dr. Rinaldo's remarks were part of a symposium entitled "The Future of Newborn Screening: Science, Policy and Technology," organized by researchers from the National Institute of Childhood Diseases and the University of Miami School of Medicine.
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