Winnipeg Free Press - PRINT EDITION
Posted: 06/24/2013 1:00 AM | Comments: 0
Prenatal genetic screening shows the medical future of offspring.
New non-invasive prenatal screening (NIPS) can predict one's medical future by betraying specific genetic loci that generate future health disorders.
"(Much like) a crystal ball through which we can glimpse one's medical (destiny)," writes Suzanne Tomlinson in a recent Harvard University report.
According to Anupama Srinivasan at Verinata Health and Diane Bianchi at Tufts Medical Center, a "molecular karyotype of the fetus (can be) determined non-invasively... (which reveals) fetal subchromosomal abnormalities."
Fetal DNA sequencing is determined through an analysis of maternal blood plasma.
"Three to six per cent of cell-free DNA in maternal blood is of fetal origin," writes researchers Glenn Palomaki and Edward Kloza at Brown University. "Measuring maternal plasma DNA detects nearly all cases (of some future medical disorders)."
"DNA sequencing of cell-free DNA from maternal blood can detect fetal chromosomal abnormalities," confirms Amy Sehnert at Verinata Health and her colleagues, B. Rhees and D. Comstock, in a recent report. "(Research shows) the power of parallel sequencing for detecting abnormal fetal karyotypes from the blood of pregnant women."
Researchers explain that prenatal test specificity across all chromosomes generates a "patient-specific individualized risk score."
In part, the new screening process has been fast-tracked because many prospective parents want to be alerted to possible medical conditions in their children.
"Reproductive genetics and assisted reproductive technology have made significant strides toward (helping) expecting parents to be able to know about their children before birth," Jaime King writes in a report in Rutgers Law Journal. "Scientists have found a way to provide diagnostic information to detect a wide range of known genetic and chromosomal conditions."
A recent study by Fieghanne Hathaway, Ester Burns and Harry Ostret shows 75 per cent of expecting parents want prenatal genetic screening to foretell mental retardation in their offspring, 54 per cent want to know about offspring future deafness, 56 per cent for blindness, 52 per cent for heart disease and 51 per cent for cancer. About half want to know of any potential health disorders that would result in the death of offspring before they reach the age of five years, and many want information regarding future violent behaviour in their kids. About one-third of parents want to know of health risks that could impact on their offspring decades in the future.
"(But) expanding NIPS testing... is likely to be highly ethically and politically controversial," cautions Peter Benn and Audrey Chapman at the University of Connecticut.
Of particular concern is that certain prenatal screening information might induce parents to opt for pregnancy termination, especially in the case of Down and other syndromes.
"Sequenon Center for Molecular Medicine (has developed) a test to determine Down syndrome in maternal plasma," Palomaki confirms.
NIPS technology can also predict Patau syndrome (Trisomy 13), Edwards syndrome (Trisomy 18), Rh factor incompatibility, cystic fibrosis and some forms of cancer.
Ethical objections to NIPS screening are intensifying.
"Prenatal diagnosis to detect genetic and other abnormalities in a fetus (could be considered) a form of discrimination against the disabled," concludes Lynn Gullion at Murdoch Institute. "But the discrimination objection... does not provide a conclusive argument against prenatal diagnosis and selective abortion."
However, rights activists Helen Houghton and Christopher Newell argue that "if prenatal diagnosis is used as a tool to eradicate... disabilities, then it does discriminate."
It is possible that some 1,500 inherited disorders might eventually be predicted by prenatal screening, according to studies at the University of Lucknow.
"(It is unethical) to use prenatal genetic testing to eliminate a disease (by) preventing the birth itself," Tomlinson writes.
Robert Alison is a zoologist and freelance writer based in Victoria.
Republished from the Winnipeg Free Press print edition June 24, 2013 A9
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