Genetic Diseases

Gregory Cochran has always been drawn to puzzles. This one had been gnawing at him for several years: Why are European Jews prone to so many deadly genetic diseases? Tay-Sachs disease. Canavan disease. More than a dozen more. It offended Cochran's sense of logic. Natural selection, the self-taught genetics buff knew, should flush dangerous DNA from the gene pool. Perhaps the mutations causing these diseases had some other, beneficial purpose. But what?

When it comes to medical care, my husband and I generally call the shots in our family. Most people would agree that this is an appropriate role for us to play, but certain medical decisions aren't normally the purview of parents. Nor should they be. Foremost among them is the decision to screen children for some genetic diseases. During the last 25 years, the number of genetic tests has increased rapidly.

My MATERNAL grandmother had Alzheimer's disease. Before she died, she forgot our names, our faces and, eventually, how to speak and think. But my grandfather's heartbreak was the most painful to witness. I remember watching the two of them on the sofa together in the months before she died. My grandfather, a sometimes severe man not overly disposed to expressions of tender emotion, cooed into my grandmother's ear: "My bride, oh my bride. I love you. Do you hear me? I love you."

The last two years have seen an exponential increase in the rate of gene discovery, thanks in large part to the advancements in so-called genotyping chip technology. These small glass or silicon platforms have made quick and easy work of simultaneously analyzing hundreds of thousands of genetic variations that exist in the human genome. The screens detect single-letter changes in the DNA code known as single nucleotide polymorphisms, or SNPs (pronounced "snips").

Will genome scan services improve people's health -- or not? So far, the limited evidence on behaviors after genetic testing has yielded mixed results. For example, a 1997 study on 426 smokers conducted at Georgetown University Medical Center found that giving smokers information on their genetic risk of lung cancer upped the motivation to quit -- but a year afterward they were no more likely to have quit smoking than people who received more general counseling.

Scientists have created the first personalized stem cells for patients with a genetic disease by rewinding their skin cells to an embryonic state, according to a study published Thursday in the online edition of Science. The researchers then converted some of those stem cells into the two kinds of brain cells that cause their crippling disease, amyotrophic lateral sclerosis, commonly known as Lou Gehrig's disease.

An experimental drug can effectively cure Duchenne muscular dystrophy in mice by correcting a genetic defect and allowing healthy muscles to develop, researchers reported Sunday in a paper published online by the journal Nature. Preliminary studies in humans with muscular dystrophy and cystic fibrosis suggest the drug is safe, well-tolerated and potentially effective, according to a team headed by H. Lee Sweeney, chairman of physiology at the University of Pennsylvania School of Medicine.

A 25-year study at 118 U.S. hospitals has demonstrated the effectiveness of a simple treatment for a mind-destroying, frequently lethal family of genetic diseases called urea cycle disorders. The diseases are rare, affecting about one in every 8,200 people, but before the discovery of the drugs used in the study, there was little that could be done for sufferers. The drugs are frequently used to treat the condition in the United States but less commonly used in other parts of the world.

Geese force-fed and then slaughtered for their livers may get their final revenge on people who favor the delicacy known as pate de foie gras: It may transmit a little-known disease known as amyloidosis, researchers reported Monday in the Proceedings of the National Academy of Sciences. A team from the University of Tennessee found that an abnormal protein called a prion can be transmitted to mice via pate and bring on disease in genetically susceptible animals.

Genetic links to breast and ovarian cancers may be hidden in some families in which there are few aunts and other female relatives, doctors have reported. Because some families are so small and with so few female relatives, doctors and patients themselves sometimes suspect their breast or ovarian cancers are sporadic, occurring with no apparent familial link. Risk, doctors have now learned, sometimes is hidden on the paternal side.