Browse the corpus

©2013 UpToDate ® Print Email American College of Obstetricians and Gynecologists Committee on Genetics recommendations for testing for fragile X syndrome 1. DNA-based molecular analysis (eg, Southern blot analysis and polymerase chain reaction) is the preferred method of diagnosis for fragile X syndrome and its premutations (FMR1 triplet repeat number). In rare cases where there is discordance between the triplet repeat number and the methylation status, the patient should be referred to a genetic specialist. 2. Women with a family history of fragile X related disorders, unexplained mental retardation or developmental delay, autism, or premature ovarian insufficiency should receive genetic counseling and should be offered genetic testing (fragile X premutation carrier screening) to assess their risk of having an affected child. 3. Prenatal testing for fragile X syndrome by amniocentesis or CVS should be offered to known carriers of the fragile X full mutation or premutation. Although it is reliable for determining the number of triplet repeats, CVS many not adequately determine the methylation status of the FMR1 gene. 4. Women who request fragile X carrier screening should be offered FMR1 DNA mutation analysis after genetic counseling that includes the risks, benefits, and limitations of screening. 5. If a woman has ovarian failure or an elevated follicle-stimulation hormone level before the age of 40 years without a known cause, fragile X carrier screening should be considered to determine whether she has a premutation. 6. Carriers of a fragile X premutation or full mutation should be referred for genetic counseling to discuss the frequency and range of potential outcomes in offspring. Options including prenatal diagnosis, preimplantation genetic diagnosis, and use of donor eggs should be discussed. Data from: ACOG committee opinion. No. 469: Carrier screening for fragile X syndrome. Obstet Gynecol 2010; 116:1008.