UK plans to expand pregnancy screening for genetic disorders

6 August 2014

The UK National Screening Committee (NSC) has recommended earlier screening in pregnancy for rare chromosomal conditions.

The current NHS Fetal Anomaly Screening Programme overseen by the NSC and offered to all pregnant women includes a combination of early serum screening for Down’s syndrome (Trisomy 21) and ultrasound scans at 10-14 and 18-20 weeks to identify signs of physical abnormalities. 

The next most common forms of trisomy (possession of an additional chromosome) seen in pregnancy are Edward’s Syndrome (Trisomy 18) and Patau Syndrome (Trisomy 13), both rare conditions with severe medical impact; most affected babies die before or shortly after birth.

Presently there is no formal process to screen for affected fetuses in pregnancy, although there are relatively high rates of detection in the context of the existing screening programme for Down’s syndrome. However, it is possible to systematically identify women at high risk of having an affected baby earlier in pregnancy via new tests within the first trimester serum screening and scan processes already in place for Down’s syndrome screening.

Earlier indication that a fetus may be affected with either of these conditions allows earlier diagnostic testing. NSC Director of Programmes Dr Anne Mackie observed that this would “give women access to support and enable them to make important choices at an earlier stage of their pregnancy”, i.e. to opt for termination of the pregnancy, or to prepare for the birth of a significantly disabled child with limited life expectancy.

On this basis, the NSC decided to recommend offering first trimester screening for Edward’s and Patau’s syndromes, subject to final consultation and confirmation of the costs of the programme. According to the BBC, a timescale for the proposed introduction of additional screening is being discussed.

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