Who should be tested for fragile X carriership? A review of 1 center's pedigrees

To determine whether following American College of Obstetricians and Gynecologists and American College of Medical Genetics recommendations would have detected carriers in pedigrees of patients diagnosed with fragile X.

Using a database of patients referred to the UT genetics clinic for evaluation of fragile X, pedigrees of cases of fragile X syndrome were analyzed.

Eight of 17 cases identified had a family history of unexplained mental retardation (MR) or fragile X MR and would have been diagnosed using current guidelines. Other findings noted in the pedigrees included autism, speech or hearing problems, attention deficit hyperactivity syndrome and behavioural disorders. No risk factors were found in 4 cases.

Using current guidelines, less than one half of fragile X carriers would have been identified during a prenatal assessment. Using other risk factors in screening would likely increase carrier detection rate.