What Is Aging? Scientists Study Role of Genes in Process

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Byline: Ann Geracimos, THE WASHINGTON TIMES

Determining how genes influence the aging process is a slippery slope, scientists engaged in the quest say.

Even defining the word "aging" raises complications, according to David Schlessinger, chief of the Laboratory of Genetics at the National Institute on Aging, an arm of the government's National Institutes of Health.

Because genes govern all life processes, there is no question of their role in the aging process. The challenge is in knowing how they behave alone and with each other and under what conditions, as well as how they react with the environment and with a person's lifestyle. Mutation, or changes in genetic behavior, is a key factor.

"What you mean by aging, and the genetics of aging, varies with different people. It's an unsettled question at present," Mr. Schlessinger says. "There are many theories of aging, and they are all persuasive. In all cases, there is an environmental component, but the response has a genetic component.

"At one extreme, [aging] can be defined as the composite of a lot of pathological problems - some people develop kidney troubles [as they age], etc. The other view is that there is an independent process of aging quite apart from pathology. Depending on the type of definition, you have a lot of different factors involved.

"Aging becomes like pornography," he concludes wittily. "You know it when you see it."

His group is studying the regulation of menopause. Premature ovarian failure, or early menopause, affects about 1 percent of women and has many causes, he notes. His lab, however, has found one gene in a small group of women - among the "considerable fraction" who have a genetic cause - which can be recognized by women born with a droopy eyelid.

"This particular syndrome involves a gene that is extremely important for the formation of follicles," he says.

Follicles in this context are small ovarian sacs containing an immature egg.

Aging also can be defined strictly as "increased maturity," Mr. Schlessinger points out. "Not all gets worse as you get old. In many cases, creativity is stable or increases. That is a positive feature of aging that has not been studied much, although new techniques would make it possible."

It's necessary, however, to take into account increased susceptibility to disease, especially diseases normally linked with age, such as Alzheimer's, osteoporosis, stroke, heart disease and cancer. The incidence of such diseases doubles roughly with every 10 years of life, he says.

"So the question is: What are genetic risk factors for those diseases? That really makes the study of the genetics of aging a study of aging-associated disease. That is a field of its own that has seen enormous progress."

Scientists interested in what Mr. Schlessinger labels "the independent process of aging" have found that genes determine about 30 percent of a person's longevity, the ability to live a longer life than is the norm.

About 50,000 Americans are centenarians - people living 100 years or more - according to census figures quoted in a 2004 report titled "Longevity Genes: Hunting for the Secrets of the Centenarians." The study was published by the International Longevity Center-USA, a nonprofit group affiliated with New York's Mount Sinai School of Medicine.

Much of the research being done in this area is credited to Dr. …