Fragile X syndrome and fragile XE mental retardation

Genetic screening in patients of reproductive age. How do you advise prospective parents who want to know specific risks?

At times, determining the actual genetic condition occurring in a family can be very difficult. The most important steps in deciding when testing is appropriate are the patient's age and family history, with special attention to ethnic background. By identifying risk factors before pregnancy, prospective parents can be fully informed about their specific risk of having a child with a genetic condition. Furthermore, the pros and cons of invasive prenatal diagnostic procedures often can be fully discussed well in advance of an actual pregnancy. Clinical geneticists and genetic counselors can provide valuable assistance when difficult questions or problems arise.

Reproductive and menstrual history of females with fragile X expansions

FRAXA premutations have been associated with premature ovarian failure (POF) or menopause before the age of 40. We have studied women in families ascertained because of a mentally retarded full mutation relative and determined their age of menopause, serum hormone levels in premenopausal individuals and the outcome of any pregnancies. Survival analysis was used as a measure of menopause and demonstrated a significant decrease in age of menopause in premutation carriers compared with their full mutation carrier and normal relatives. Serum FSH was also raised in premutation carriers, although oestradiol, inhibin A and inhibin B were not significantly different. However, we did not find an excess of dizygous twins or pregnancy loss/trisomies, both of which are associated with aging ovaries. Thus premutation carriers as a group have an earlier menopause and raised serum FSH but do not appear to manifest other features of an aging ovary.