Improved prenatal detection of fra(X)(q27.3): Methods for prevention of false negatives in chorionic villus and amniotic fluid cell cultures
- 1 February 1991
- journal article
- research article
- Published by Wiley in American Journal of Medical Genetics
- Vol. 38 (2-3), 447-452
- https://doi.org/10.1002/ajmg.1320380262
Abstract
The reliable detection of fra(X)(q27.3) in prenatal samples is important for providing genetic counseling. We have identified 5 new cases of prenatal fragile X [fra(X)] detection in 3 chorionic villus sample (CVS) and 2 amniotic fluid (AF) cell cultures. In 4 of the 5 cases, either excess thymidine (THY) or a combination of THY and 5‐fluorodeoxyuridine (FUdR) was clearly superior to FUdR alone as fra(X) inducers. Amniocytes from one case were cultured only in RPMI‐1640 and later exposed to FUdR or THY separately. They showed only 2% fra(X) while parallel cultures initiated in Chang medium and incubated in RPMI for at least 7 days (recovery) before fra(X) induction exhibited strikingly increased fra(X) frequencies. Chang medium alone will not allow fra(X) induction in AF (Jenkins EC, Brown WT [1986]: “Genetic Disorders and the Fetus: Diagnosis, Prevention and Treatment.” New York: Plenum Press, pp 185–204). Now, using CVS cells, we report that only 1% and 0% fra(X) were detected using FUdR or THY in cells cultured in RPMI for 4 days after removal from Chang medium. Cells with 7 days “recovery” in RPMI exhibited increases from 2 to 6%. Therefore, we have found that Chang medium is very helpful when the appropriate recovery time in another medium is allowed before fra(X) induction. Some false negative reports can be attributed to: induction in Chang medium alone; lack of sufficient recovery time after initiating cells in Chang before induction; and unavailability of the excess THY fra(X) induction system. In conclusion, 1) multiple induction systems, including a combination of FUdR/THY, and 2) initial culture of cells in Chang medium with more than a 4 day recovery period in RPMI or another appropriate medium, enhance optimal conditions for prenatal fra(X) detection. These modifications should reduce the possibility of false negatives thereby improving the reliability of prenatal fra(X) detection.Keywords
This publication has 29 references indexed in Scilit:
- Fragile X expression: Use of a double induction systemAmerican Journal of Medical Genetics, 1991
- Prenatal diagnosis of the fragile X – The Australasian experienceAmerican Journal of Medical Genetics, 1988
- Prenatal diagnosis of fragile X syndrome by placental (chorionic villi) biopsy cultureAmerican Journal of Medical Genetics, 1988
- Recent experience in prenatal fra(X) detectionAmerican Journal of Medical Genetics, 1988
- Prenatal diagnosis of the fragile X using thymidine inductionPrenatal Diagnosis, 1987
- Prenatal diagnosis of the fragile X syndrome using fetal blood and amniotic fluidPrenatal Diagnosis, 1987
- Second international workshop on the fragile X and on X‐linked mental retardationAmerican Journal of Medical Genetics, 1986
- Fragile X: Carrier detection in pregnancyAmerican Journal of Medical Genetics, 1986
- Prenatal diagnosis of the fra(X) syndromeAmerican Journal of Medical Genetics, 1986
- The prenatal detection of the fragile X chromosome: Review of recent experienceAmerican Journal of Medical Genetics, 1986