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Study questions screening for Fragile X Syndrome

2 August 2010
Appeared in BioNews 569

Genetic counselling for women and parents undergoing Fragile X syndrome (FXS) screening needs improvement, according to a recent review. The review also called for more studies into the benefits of population-wide screening for FXS.

Australian researchers examined studies into population-based screening programmes for FXS in newborns and women of reproductive age published between 1991 and 2009. Dr Melissa Hill from the Murdoch Children's Research Institute, Melbourne and her team found affected families knew little about FXS compared to other disorders like cystic fibrosis, posing a challenge to genetic counsellors.

Available evidence was also limited. The team found only one study looking at newborns and ten looking at women of reproductive age. The studies were largely observational and the psychosocial aspects of FXS were largely ignored.

The review also found screening adult women is easier than prenatal screening or testing newborns and preferred by women. Women diagnosed as a carrier of FXS mainly agreed to fetal testing with some opting for a termination. Uptake of testing ranged from 7.9 per cent to 92 per cent in prenatal studies and 79 percent in the newborn study.

FXS is the most common cause of inherited mental impairment, with symptoms ranging from learning disabilities to more severe cognitive or intellectual disabilities. In FXS, a section of the X chromosome becomes expanded. When normal, the FMR1 (fragile X mental retardation 1) gene makes a protein necessary for brain development. When this is faulty little or none of the protein is made.

The syndrome affects around one in 3,600 men but is much less common in women. This is because men only have one X chromosome whereas women have a second, which can be used instead of the faulty one. Women can also be carriers of the condition.

The study is published in Genetics in Medicine.

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