7 April 2008
A recent review in the journal Paediatrics sets out a useful summary of pertinent ethical, legal and social issues for expanding newborn screening programmes. In the UK, there is a national Newborn Screening Programme which uses bloodspot samples to screen for the single-gene disorders phenylketonuria (PKU), congenital hypothyroidism, sickle cell disease and cystic fibrosis; the latest addition to the programme is screening for MCADD (see previous news). Many other countries have similar schemes, although the range of conditions screened for varies; in the US, it has been proposed that is should include a minimum of 29 disorders (see previous news), and potentially many more - including conditions for which there are as yet no effective interventions .
The emerging problem with newborn screening is that technical capability is outstripping proven clinical utility. The key reason for including a condition in newborn screening panels is where early detection allows intervention to minimize or prevent harm; for example, restricting dietary intake of phenylalanine prevents the severe mental retardation associated with PKU. However, the clinical benefits of diagnosis are not always so clear-cut; the value of early cystic fibrosis diagnosis has been fiercely debated, although evidence has accumulated to support it. Some suggest that diagnosis of a serious disease is of value in itself, if only because it prevents unnecessary additional testing; others say that to provide information that lacks clinical utility is pointless, and even cruel.
With rapidly developing techniques for high-throughput analysis such as tandem mass spectroscopy (MS/MS), it has become increasingly feasible to test for multiple genetic diseases. The US-based authors of the new paper use Fragile X syndrome as a prototype of an untreatable condition which cost-effective screening may soon become available (see previous news). Fragile X is the most common inherited form of learning disability; care of affected families is complicated by the fact that female carriers of ‘pre-mutation’ alleles are not usually significantly affected themselves, and may or may not transmit a full blown mutation allele to their offspring. The authors identify several key areas of concern [Bailey DB et al. Pediatrics 2008;121(3):e693-704].
Psychosocial harm to the family of the affected child – for example, increased levels of parental anxiety or weakened parental bonding with the child – is identified as a potential problem. This could also be serious where a phenotypically normal child might be identified as affected, or as a carrier for a disease; in such instances the possibility of discrimination or stigmatisation is noted. The prospect of effectively overwhelming genetics services by increasing referrals and demand for genetic counselling and screening of family members is raised; the necessity for properly informed consent for expanded screening would not only increase the burden for providers, but could potentially also reduce participation in standard screening programmes. The authors suggest that consultation with “scientists, policy makers, ethicists, practitioners, and other citizens” is required to consider the underlying aims of newborn screening, and to establish a national newborn screening research network.
Comment: This paper raises the interesting suggestion that we are in a process of moving from the traditional public health model for screening as a means to prevent irreversible and serious harm, to a new model whereby screeningis a service that provides wider but less immediate or obvious benefits. The authors propose that given “low levels of genetic literacy combined with public ambivalence and perhaps skepticism about the value of genetic information”, the public health community should try to engage with the public on this issue. Certainly, this is an arena where practitioners of public health genomics should have a voice; the importance of achieving “responsible and effective application” of biomedical advances for health – and the necessity to weigh potential benefits against possible harms in so doing – is well illustrated by this example.