MOLECULAR FRAGILE-X SCREENING IN NORMAL-POPULATIONS

In December, 1993, we initiated a pilot project in which DNA fragile X (fraX) testing was offered during routine prenatal or genetic counsel ing to all pregnant women seen at the Genetics & IVF Institute, most o f whom were referred for the indication of advanced maternal age, A br ochure on fragile X syndrome was sent to each patient prior to her app ointment and was reviewed by a counselor or physician during the couns eling session, As of June 1995, 3,345 patients were offered testing; 4 74 women with no identified family history of mental retardation or le arning disability and 214 women with a positive family history accepte d the test on a self-pay basis, The second population screened was 271 potential donors in our anonymous egg donor program, DNA from blood w as tested by Southern blot using EcoRI/EagI and StB12.3. If an expansi on was detected, CGG repeat number was determined by PCR-based analysi s, Among the 474 patients with unremarkable family histories, three fr aX carriers were identified (repeat sizes = 60+), whereas none were fo und in the 214 patients with a positive family history, Among the pote ntial egg donors, two high borderline patients were identified (repeat sizes = between 50 and 59), Our ongoing study indicates that screenin g of pregnant or preconceptual populations for fraX carrier status usi ng DNA testing is accepted by many patients and is an important additi on to current medical practice. (C) 1996 Wiley-Liss, Inc.