Introduction
Prenatal cytogenetic analysis requires the isolation of metaphase chromosomes and takes 7-14 days for the final results. This waiting period tends to cause psychological distress for pregnant women and their families. Aneuploidies of 5 chromosomes (13, 18, 21, X, Y) account for 95% of the chromosomal aberrations that cause infants born with defects. Fluorescent labeled DNA probes of the 13, 18, 21, X, Y chromosomes can be used on uncultured cells obtained directly from amniotic fluid. The FISH rapid technique allows to reliably detect numerical aberrations for these chromosomes.
While not all chromosome abnormalities can be identified simply by counting specific chromosomes within a cell, the majority of the most common abnormalities of chromosome number, including Down syndrome (trisomy 21), trisomy 18, trisomy 13, Klinefelter syndrome (47,XXY), triple-X syndrome (47,XXX), Turner syndrome (45,X) and 47,XYY can be reliably determined. The FISH analysis does not detect structural chromosome abnormalities, mosaicism, and other numerical chromosome abnormalities (excluding X, Y, 13, 18, and 21). In addition, false-positive or negative results, as well as maternal cell contamination, have been demonstrated in prenatal FISH analysis. It is recommended (e.g. American College of Medical Genetics) that irreversible therapeutic action should not be initiated on the basis of FISH results alone.
Introduction
Prenatal cytogenetic analysis requires the isolation of metaphase chromosomes and takes 7-14 days for the final results. This waiting period tends to cause psychological distress for pregnant women and their families. Aneuploidies of 5 chromosomes (13, 18, 21, X, Y) account for 95% of the chromosomal aberrations that cause infants born with defects. Fluorescent labeled DNA probes of the 13, 18, 21, X, Y chromosomes can be used on uncultured cells obtained directly from amniotic fluid. The FISH rapid technique allows to reliably detect numerical aberrations for these chromosomes.
While not all chromosome abnormalities can be identified simply by counting specific chromosomes within a cell, the majority of the most common abnormalities of chromosome number, including Down syndrome (trisomy 21), trisomy 18, trisomy 13, Klinefelter syndrome (47,XXY), triple-X syndrome (47,XXX), Turner syndrome (45,X) and 47,XYY can be reliably determined. The FISH analysis does not detect structural chromosome abnormalities, mosaicism, and other numerical chromosome abnormalities (excluding X, Y, 13, 18, and 21). In addition, false-positive or negative results, as well as maternal cell contamination, have been demonstrated in prenatal FISH analysis. It is recommended (e.g. American College of Medical Genetics) that irreversible therapeutic action should not be initiated on the basis of FISH results alone.