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© 2007 American Public Health Association
DOI: 10.2105/AJPH.2006.107367
LETTER |
Nancy S. Green is with the March of Dimes, White Plains, NY. Thomas H. Murray is with the Hastings Center, Garrison, NY.
Correspondence: Requests for reprints should be sent to Nancy S. Green, MD, Medical Director, March of Dimes, 1275 Mamaroneck Ave, White Plains, NY 10605 (e-mail: ngreen{at}modimes.org).
We thank Ross for suggesting a potential improvement in newborn screening (NBS) for cystic fibrosis (CF) by adding a second-tier enzyme-linked immunosorbent assay for pancreatic-associated protein for those samples screening positive by immunoreactive trypsinogen (IRT).1 The addition of pancreatic-associated protein may improve the specificity of screening, perhaps bypassing some of the difficulties that we note with secondary DNA-based CF screening as it is currently practiced.2 However, the limitations of DNA-based screening by assay of only a minority of the known mutations in the CF gene can be better addressed by increasing the number of mutations analyzed. Accurate genotyping will be useful in confirming disease detection and could provide genotype-phenotype predictions of disease course and related clinical utility,3 such as for clinically less severe variants of galactosemia (i.e., the Duarte mutation) or CF (e.g., the R117H mutation). Even as protein assays progress, NBS will increasingly use DNA as a tool for the identification and treatment of children affected by CF and other disorders. Therefore, programs will be best served by improving both protein- and DNA-based screening strategies, making them more accurate, predictive, and inclusive for the diverse population of neonates.
Incorporating new technologies to improve NBS and decrease health disparities remains an essential element of providing optimal public health service. Some disorders may require primary DNA-based screening. For example, a screening assay has recently been reported for severe combined immune deficiency (SCID).4,5 While we had raised questions about NBS for SCID because treatment requires bone marrow cell transplantation,2 recent evidence suggests that transplant with banked cord blood or partially matched donor hematopoietic stem cells for treatment—and cure—of SCID can be made widely available6,7 and may be cost effective.8 Such evidence reminds us that NBS should remain open to new opportunities for screening and treatment.
Finally, we emphatically echo Ross’s call that NBS should help to redress, not exacerbate, health care disparities. The screening component of NBS is as close to a universal health service as exists in the United States. We must also assure that all children identified by NBS receive the care they need. The hodgepodge of eligibility criteria and funding streams that characterize health care in the United States makes this a difficult challenge, the solution to which will be found in policy, not technology.
References
1. Sarles J, Berthezene P, Le Louarn C, et al. Combining immunoreactive trypsinogen and pancreatitis-associated protein assays, a method of newborn screening for cystic fibrosis that avoids DNA analysis. J Pediatr. 2005;147:302–305.[CrossRef][Web of Science][Medline]
2. Green NS, Dolan SM, Murray TH. Newborn screening: complexities in universal genetic testing. Am J Public Health. 2006;96:1955–1959.
3. Green NS, Pass KA. Neonatal screening by DNA microarray: spots and chips. Nat Rev Genet. 2005; 147–151.
4. Chan K, Puck JM. Development of population-based newborn screening for severe combined immunodeficiency. J Allergy Clin Immunol. 2005;115:391–398.[CrossRef][Web of Science][Medline]
5. McGhee SA, Stiehm ER, Cowan M, et al. Two-tiered universal newborn screening strategy for severe combined immunodeficiency. Mol Genet Metab. 2005; 86:427–430.[CrossRef][Web of Science][Medline]
6. Myers LA, Patel DD, Puck JM, Buckley RH. Hematopoietic stem cell transplantation for severe combined immunodeficiency in the neonatal period leads to superior thymic output and improved survival. Blood. 2002;99:872–878.
7. Lindegren ML, Kobrinsky L, Rasmussen SM, et al. Applying public health strategies to primary immunodeficiency diseases: a potential approach to genetic disorders. MMWR Recomm Rep. 2004;53:1–29.[Medline]
8. McGhee SA, Stiehm ER, McCabe ERB. Potential costs and benefits of newborn screening for severe combined immunodeficiency. J Pediatr. 2005;147:603–608.[CrossRef][Web of Science][Medline]
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