antenatal and newborn screening programme

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Fragile X

This recommendation has been archived and is no longer regularly reviewed by the UK NSC.

Fragile X is one of the most common identifiable forms of inherited intellectual disability. It has a prevalence of about 1 in 4,000 males and 1 in 8,000 females.

Fragile X is one of the most common identifiable forms of inherited intellectual disability. It has a prevalence of about 1 in 4,000 males and 1 in 8,000 females.

Based on the last UK NSC review of this condition that occurred in April 2026, screening for FXS during pregnancy is not recommended. This is because:

• there is a lack of evidence on the accuracy of the test
• some babies with a positive test result may never have symptoms
• some families may have to make difficult decisions on pregnancy without knowing if their baby will develop symptoms
• there is a lack of evidence that screening would improve outcomes in children compared to usual health care

This condition has been archived due to there being minimal evidence development for screening for FXS during pregnancy. Any future requests to consider the evidence on this topic should be submitted via the UK NSC’s open call for topics.

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