CARRIER DETECTION AND CLINICAL UNCERTAINTY: THE CASE FOR PUBLIC HEALTH ETHICS

In their response to our commentary, Ross and Clayton provide a clinical rationale for the disclosure of carrier status results generated incidentally through newborn screening for sickle cell disorders, suggesting that carriers are at increased risk for heat stroke in extreme conditions.¹ A better case for nondisclosure, they argue, might be made for carrier status for cystic fibrosis, as there are no data to suggest that cystic fibrosis carriers bear health risks.¹ We welcome the opportunity to respond.

Our commentary was written in response to existing debates that assume the benign nature of carrier status. Guiding documents^2–4 have not suggested a clinical rationale for disclosure. Instead, there is an apparent consensus that it is unethical to withhold carrier information. We argued that withholding data is not the only moral harm to consider. In fact, in the context of a public health intervention, without informed consent, routine disclosure actually involves a requirement that parents learn their infant's carrier status—an imperative that is itself morally troubling.⁵

While it is reasonable to consider the clinical implications of carrier status in this debate, in contrast to Ross and Clayton, we believe that the nature of the health risks from sickle cell carrier status strengthen the case for nondisclosure. This is because newborn screening is a public health intervention, where the burden of proof rests with those who sanction screening to demonstrate the value of early disease identification and to ensure that its benefits outweigh its harms. To disclose carrier status because of the clinical risks it identifies rather than as an incidental finding of no clinical significance evokes a clinical calculus. Yet carrier status cannot possibly meet the clinical standard for screening and disclosure.

Moreover, guidance regarding the clinical significance of sickle cell carrier status is contradictory. In the United Kingdom, parents of sickle cell carrier infants are warned of the risks of general anesthesia and surgery⁶; in the United States, while other risks are identified, these specific harms are not.⁷ In the current era of genetic risk information, as we learn more and more about genetic variants that create disease susceptibilities in partial and complex ways, such uncertainty is to be expected. Cystic fibrosis carrier status may not prove to be an exception.⁸

In the context of clinical uncertainty, we hold firm to our conclusion that public health ethics, and not a clinical calculus, must guide population-wide newborn screening policy.