Preconception and antenatal screening for the fragile site on the X-chromosome

Abstract

Background: Fragile X is the most common cause of mental retardation after Down syndrome. It is the commonest inherited cause of mental retardation, and results from a dynamic mutation in a gene on the long arm of the X chromosome. Various strategies are used for prenatal screening. Objectives: To determine whether preconceptional or antenatal screening for fragile X carrier status in apparently low-risk women confers any additional benefit over the existing practice of offering testing to women thought to be at increased risk. Search methods: We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (October 2008). Selection criteria: Randomised clinical trials comparing women being tested regardless of family history (intervention group) with women tested only when there is a family history of either fragile X and/or other undiagnosed mental illness/impairment (control group). Data collection and analysis: Three review authors independently assessed trial quality. Main results: No trials were included. Authors' conclusions: No information is available from randomised trials to indicate whether routine preconceptional or antenatal screening for fragile X carrier status confers any benefit over testing women thought to be at increased risk.