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Simple no-risk prenatal blood test may detect vast range of genetic disorders

This article was published in Scientific American’s former blog network and reflects the views of the author, not necessarily those of Scientific American


Prenatal genetic tests such as amniocentesis (drawing some amniotic fluid from around a 16-week fetus) always carries a small risk of miscarriage. Now, a partnership between a group of Chinese researchers and a San Diego biotech company may result in a simple no-risk blood test that detects defects caused by single-gene mutations.

Chinese University of Hong Kong scientists report in the Proceedings of the National Academy of Sciences that they devised a technique that locates a fetus's DNA molecules in blood samples taken from its mother. The fetal DNA or genetic material, which tends to be shorter than that of the mom, is duplicated and subjected to a “molecular counting” technique that tallies both mutant and normal genetic material.  The new method overcomes what had been the major obstacle to such testing: distinguishing fetal DNA inherited from mom from mom's own DNA,

The range of single-gene disorders is vast, from cystic fibrosis to sickle-cell anemia  (a disease in which abnormal amounts of iron-rich protein or hemoglobin cause normally round red blood cells to be sickle- or c-shaped and to clump together, blocking blood flow to limbs and organs).  Biotech company Sequenom, which is already developing a blood test for Down’s Syndrome, says it plans to begin work on a commercial test for single-gene disorders.

“If you look at the very rare disorders, you’re into the five to ten- thousand range,” of diseases that might be detected with this test, says Harry Stylli, president and chief executive of the California-based company, which licensed the technology from the university. He notes that, eventually, it may be possible for physicians to order a customized battery of tests based on a patient’s risk profile.


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Gary Stix, Scientific American's neuroscience and psychology editor, commissions, edits and reports on emerging advances and technologies that have propelled brain science to the forefront of the biological sciences. Developments chronicled in dozens of cover stories, feature articles and news stories, document groundbreaking neuroimaging techniques that reveal what happens in the brain while you are immersed in thought; the arrival of brain implants that alleviate mood disorders like depression; lab-made brains; psychological resilience; meditation; the intricacies of sleep; the new era for psychedelic drugs and artificial intelligence and growing insights leading to an understanding of our conscious selves. Before taking over the neuroscience beat, Stix, as Scientific American's special projects editor, oversaw the magazine's annual single-topic special issues, conceiving of and producing issues on Einstein, Darwin, climate change, nanotechnology and the nature of time. The issue he edited on time won a National Magazine Award. Besides mind and brain coverage, Stix has edited or written cover stories on Wall Street quants, building the world's tallest building, Olympic training methods, molecular electronics, what makes us human and the things you should and should not eat. Stix started a monthly column, Working Knowledge, that gave the reader a peek at the design and function of common technologies, from polygraph machines to Velcro. It eventually became the magazine's Graphic Science column. He also initiated a column on patents and intellectual property and another on the genesis of the ingenious ideas underlying new technologies in fields like electronics and biotechnology. Stix is the author with his wife, Miriam Lacob, of a technology primer called Who Gives a Gigabyte: A Survival Guide to the Technologically Perplexed (John Wiley & Sons, 1999).

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