Tuesday, December 10, 2013   Unraveling Your DNA's Secrets  Do-
it-yourself genetic tests promise to reveal your risk of coming
down with a disease. But do they really deliver?  By Nancy Shute
Posted 12/31/06 Page 3 of 7  Until now, most people who
encountered genetic testing were expectant women, who are
routinely offered screening to see if they're carriers of the
genes for cystic fibrosis, sickle cell anemia, or Tay-Sachs.
Amniocentesis and chorionic villi sampling tests can reveal
genetic disorders in a fetus. Newborns are screened for dozens
of genetic disorders like phenylketonuria, a metabolic disease,
which are treatable if detected early. Preimplantation genetic
diagnosis is increasingly being used to screen embryos for fatal
disorders–and also to pick the child's sex.  So if embryos can
have a molecular crystal ball, why not grownups? Alas, using
genetic tests to predict eventual disease is a lot tougher than
diagnosing if the person already has a disease. "It could
account for the disease, or maybe