Newborn Screening: Present and Future

Abstract

Currently, in New Zealand, children at birth have their heel pricked to test for metabolic conditions which, if found early enough, can be treated. The present New Zealand newborn metabolic screening programme is a competent and successfully run programme with good detection and participation rates. The programme staff is committed to the success of newborn screening, is progressive in attitude towards the benefits of screening and fosters good links with other international programmes.

The programme has avoided negative publicity, and has carefully managed access to the Guthrie cards in the interests of maintaining public confidence. New Zealand is well placed to have a flexible and responsive screening programme, given the small population; the single medical contact for each child (the lead maternity carer); a nationally consistent screening panel; centralised testing; and public funding. New Zealand is following international trends in newborn screening but not in too hurried a fashion. Even before expansion, the New Zealand programme was screening for a respectable number of serious disorders (more than, for example, the United Kingdom). New Zealand has been able to use the implementation lag to absorb knowledge about and experience of these new technologies from overseas, and to put in place adequate support services, such as the employment of a clinical metabolic specialist, before launching tandem mass spectrometry (MSMS) screening.

There is little public awareness of the successful New Zealand newborn programme, beyond recognition that the ‘heel prick test’ is a routine procedure for newborns. The National Metabolic Screening Programme has been consulting on various aspects of the programme and the storage and use of the Guthrie cards. This consultation is a positive move given the anecdotal evidence of growing anxiety surrounding the use of DNA samples and Guthrie cards. A small but growing number of parents who are requesting the return of the cards points to concern about potential uses of the DNA samples. This concern may have implications for the screening programme in the future.

More public education and information regarding the programme, particularly in antenatal classes and on the internet, should be made available to the general population. Publications, whether scientific or popular, about newborn screening should be made more widely available to parents and members of the public who are seeking more information than is currently contained in educational pamphlets. Audit, epidemiological and cost-effectiveness data should be gathered from the programme.

Given the constrained levels of financial support, and small number of key staff, this research would best be done in association with other researchers. Screening expansion is an exciting move for many and the programme expects that an additional five to ten children with genetic disorders will be detected through the programme per annum. The MSMS screening is also to be used as a metabolic diagnostic tool. Given the expansion of newborn screening, and the versatility of the new technology and its potential for disease prevention, the purchase of MSMS was perhaps worthy of better governmental support, rather than the programme’s reliance on a children’s charity for financial support.

The newborn metabolic screening programme can be classed as a genetic service. At present, there is unofficial and ad hoc national co-ordination with respect to genetic services. There is apparently a review underway of the 2003 National Health Committee (NHC) report on co-ordination of genetic testing in New Zealand by the New Zealand District Health Boards, presumably with a view to implementation of at least some of the report; there is no other information available on this review at present. Newborn metabolic screening should be acknowledged in future genetic coordination initiatives; though, equally, the programme legitimately belongs within the mandate of screening services.

When scientifically accurate, clinically useful, cost-effective, high-throughput screening processes are available, the pros and cons of inclusion of early onset, untreatable disorders, such as lysosomal or peroxisomal storage disorders, should be publicly discussed.

If screening of untreatable disorders is introduced, then there must be improved education so that parents are aware of the implications of screening. In the future, it is likely that DNA screening for individual disorders will be introduced as adjunct tests to the metabolic screening programme. In view of the speed at which science is developing in genetics, it is impossible to say, with any certainty, what the longer-term future holds for newborn screening or even whether the screening time point might move to (non-invasive?) antenatal screening. Whole genome sequencing remains likely in the future, although how and when this information might be used, after the initial sequencing process, remains to be seen.

Expansion of newborn screening into DNA screening will require more characterisation of minority populations in New Zealand. It is likely that there will be differing allele frequencies for various disorders in these populations, compared with populations of Northern European descent (as for cystic fibrosis in the United States). It is also possible that a small number of genetic disorders, rarely found in Northern European populations, are more commonly found in minority populations here. If any were identified, there would be merit in evaluating them for screening.

The current Wilson-Jungner criteria, which have been used as a foundation for newborn screening and which were originally formulated in 1968 for chronic adult disorders, should be reformulated for newborn screening.