Fragile X syndrome prenatal diagnosis: parental attitudes and reproductive responses

Fragile X syndrome (FXS) is the most common inherited form of mental retardation. It is caused by a CGG repeat expansion, which results in silencing of the FMR1 gene. Individuals can be considered as normal (<55 repeats), carriers (55-200) and affected (>200) for the FMR1 gene. FXS prenatal diagnosis is feasible and we present the results from 213 FXS prenatal diagnoses performed in our centre. Reasons for referral were family history of FXS or undiagnosed mental retardation (MR). It is worth mentioning that 64% of mothers were not aware of their status before the test, so prenatal and mother tests were performed at the same time. Among those women referred for family history of unknown MR, 17.6% were FXS carriers. We also evaluated the attitudes and perceptions of the syndrome of 52 FXS carriers. Most of them had been diagnosed as carriers when the child was already born and the most common feeling was sadness, followed by impotence and guilt. The majority of them had received genetic counselling and they considered it useful. Regarding reproductive options, prenatal diagnosis was chosen by 40.5% of women. Prenatal diagnosis for FXS is a good reproductive option, and it should be carried out whenever family history of MR is present. A high percentage of FXS carriers are detected following this approach.