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Screening for fragile X is cost effective and accurate

BMJ 1997; 315 doi: http://dx.doi.org/10.1136/bmj.315.7102.205i (Published 26 July 1997) Cite this as: BMJ 1997;315:205
  1. Caroline White
  1. London

    Screening for the fragile X syndrome is both accurate and cost effective and should now be considered for inclusion in a national screening programme, concludes a new report commissioned by the NHS Executive's research and development programme on health technology assessment (Journal of Medical Screening 1997;4:60-94).

    DNA testing to screen for the disorder is now technically feasible. However, although the technology has been available for some time, there has been some reluctance to screen for the disorder in the NHS because of the lack of conclusive evidence of its likely effectiveness and cost. The genetic defect responsible for the fragile X syndrome, which affects 1 in 4000 boys and 1 in 8000 girls, was discovered in 1991. The syndrome is the most common inherited mental disorder, with about 200 cases reported every year in young children.

    At an estimated cost of over £90000 ($151000) for each case detected, routine antenatal screening for the fragile X syndrome is three times as expensive as that for Down's syndrome. But this must be offset, say the report's authors, against the costs of lifetime care for a child with the fragile X syndrome, which exceed £700000. The cost of screening is likely to drop if it became routine.

    The available data suggest that DNA screening for the disorder would detect all cases. This compares with 60-70% of cases for Down's syndrome. As the procedure is accurate the need for amniocentesis is reduced, by a factor of 10 compared with Down's syndrome. Concern has been expressed, however, that the data on Down's syndrome are quite old, making direct comparisons difficult. Down's syndrome is the most common cause of mental disorder, with about 1000 cases a year.

    “As with other serious congenital abnormalities, many women are likely to want to know their risk. Armed with this knowledge, women and their partners can make informed reproductive choices,” comments Professor Howard Cuckle of the Centre for Reproductive Growth and Development at the University of Leeds, and one of the report's authors.

    The report will be submitted to the National Screening Committee and is also likely to be considered by the committee's antenatal screening subgroup together with reports on Down's syndrome and cystic fibrosis.”

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