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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.

Image by iStockphoto

3 Comments

1. 1. toothlful 11:18 PM 11/25/08

   isn't it curious that nearly 4000 diseases have been linked to mutations, but not one truly beneficial mutation has yet to be documented.
   
   harmful mutations will lead to the death and extinction of all evolutionary theories which depend upon mutations as their prime mover!

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2. 2. ductileironman in reply to toothlful 08:35 AM 11/26/08

   Your statement is false.
   It took 5 seconds to find this statement in a web link:
   
   Patients with the QQ or H7H7 genotype had a decreased risk of myocardial infarction (odds ratios, 0.08 [95 percent confidence interval, 0.01 to 0.9] and 0.22 [95 percent confidence interval, 0.08 to 0.63], respectively).
   
   and this from Wiki:
   
   Although many mutations are deleterious, mutations may have a positive effect given certain selective pressures in a population.
   
   For example, a specific 32 base pair deletion in human CCR5 (CCR5-�32) confers HIV resistance to homozygotes and delays AIDS onset in heterozygotes.[8] The CCR5 mutation is more common in those of European descent. One theory for the etiology of the relatively high frequency of CCR5-�32 in the European population is that it conferred resistance to the bubonic plague in mid-14th century Europe. People who had this mutation were able to survive infection; thus, its frequency in the population increased.[9] It could also explain why this mutation is not found in Africa where the bubonic plague never reached. Newer theory says the selective pressure on the CCR5 Delta 32 mutation has been caused by smallpox instead of the bubonic plague.[10]
   
   so, to say that no beneficial mutations were found is not true.
   
   Sadly, the information found by the mentioned tests will be more likely used to decide on keeping or aborting a baby instead of finding treatment to mitigate the defects that were found.

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3. 3. toothful 11:28 PM 11/26/08

   there are negative effects on t-cell function caused by CCR5 Delta32, also.
   
   information concerning this mutation is, yet, being gathered.
   evidence concerning susceptibility for west nile virus and certain forms of arthritis are connected to this mutation. perhaps there will be more negative results discovered in the future.
   
   remember the sickle cell mutation - "good" for malaria, but the horrible disease called sickle cell anemia far outweighed the so-called beneficial effect! i don't know of anyone who would like to have this genetic mistake.
   
   what about bacteria with the mutation which makes them antibiotic resistant? there was cell damage here, also; resulting in a loss in capability to process proteins (food). they can only thrive in an artificial environment that kills off their competition; but, when exposed to the natural realm, they can not compete and lose out.
   
   for the sake of argument, let's say that there is one beneficial mutation to every several thousands of harmful ones. how far would you expect to "progress" going one step forward and thousands backward?
   
   if you think mutations (mistakes) produced the "new and improved" - progressively more complex - result of modern man from bacteria; then, why don't you start a random dimension changing blueprints business and see how well you do in the construction market?
   

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