PHILADELPHIA â€” We often hear that â€śknowledge is power.â€ť But, that isnâ€™t always the case, especially when the knowledge pertains to the health of an unborn child, with murky implications, at best. A new study, led by researchers from the Perelman School of Medicine at the University of Pennsylvania, begins to document this exception to the general rule.
Barbara Bernhardt, MS, CGC, a genetic counselor at the Hospital of the University of Pennsylvania, and colleagues contacted a small group of women who are participating in a larger Columbia University study investigating the use of a genetic test called a DNA microarray to identify the possibility of prenatal chromosomal abnormalities. Bernhardt is also co-director of the Penn Center for the Integration of Genetic Healthcare Technologies.
The studyâ€™s goal: To document a womanâ€™s experience upon learning that her childâ€™s genetic material contained chromosomal abnormalities. The womenâ€™s responses to this type of news were mostly negative, ranging from saying they â€śneeded supportâ€ť after getting the results to describing the results as â€śtoxic knowledge,â€ť that they wish they hadnâ€™t received.
DNA microarrays represent a relatively new approach to genetic testing. Classically, chromosomal abnormalities are detected with karyotyping, which uses DNA staining and microscopy to identify such large-scale abnormalities as trisomy 21, associated with Downâ€™s syndrome. Yet the technique lacks the resolution to detect smaller â€“ yet still significant -- chromosomal changes.
Thatâ€™s where DNA microarrays come in. Microarrays use an array of DNA â€śprobesâ€ť to search for matching bits of DNA from across the genome. In theory, if a piece of DNA is missing or duplicated, that change can be detected on a microarray, even if it is too small to be detected by karyotyping.
DNA microarrays are often used by physicians following birth to identify chromosomal abnormalities in children with unexplained developmental delays or congenital defects. However, the technique is also being applied prenatally. The problem, though, unlike some genetic changes that definitely lead to disease, is that the significance of the changes DNA microarrays identify (called copy-number variants) isnâ€™t always clear. Nor is it necessarily obvious what actions parents, doctors, and genetic counselors should take in light of the findings.
Bernhardt set out to document the experiences of women receiving such information. Of the 4,450 women enrolled in the Columbia University trial, Bernhardt and her team selected 54 who had received chromosome microarray results that showed abnormalities in the previous six months. Of those, they interviewed 23 regarding the subjectsâ€™ recollections of their informed-consent discussions, genetic counseling, test results, and follow-up.
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