(Bloomberg News) Exactly why James Markam is alive and well is a bit of a mystery. The octogenarian has lost four siblings to cancer, heart disease and emphysema, all before they reached the age of 62. Yet the retired airline executive recalls only one bout of sickness, culminating with a chest cold, 50 years ago.

Scientists are taking a deep look at Markam's genetics to see if there's something protecting him from illnesses that affect others his age, such as Alzheimer's, cancer, diabetes and heart disease. Markam, 83, is one of more than 1,300 individuals identified as having what Eric Topol, director of the Scripps Translational Science Institute, called "Teflon-coated" genes.

"We think it's in the genome in these individuals," said Topol, who is leading research of healthy older people called the Wellderly Study at the La Jolla, California-based institute. "You don't see any environmental thing that would be explaining this."

The study, the first focused on healthy aging, expects to have the first set of participants' genes sequenced by the end of the year, said Cliff Reid, chief executive officer of Mountain View, California-based Complete Genomics Inc., which is doing the work for free.

Scientists and pharmaceutical companies are closely watching Scripps' research project and others like it, eager for clues that may help them develop new treatments to ward off diseases that have long afflicted the elderly. For drug companies such as Merck & Co. and Eli Lilly & Co., the hope is that the research will lead to the creation of new billion- dollar blockbuster therapies.

Human Genome

The human genome is a transcript of an individual's DNA code containing the instructions for making cells in the body. Scientists say the genome may provide keys to understanding health and disease.

The projects reflect researchers' evolving views of how genetic mutations cause disease. While scientists once thought common genetic variants were responsible for many common diseases, recent research has changed that view. Instead, combinations of the millions of rare variants are the more likely culprits behind wide-spread ailments, making them difficult to identify.

Creating a clean map of a healthy genome that can be quickly compared to DNA that makes a person vulnerable to illness, the thinking goes, will allow researchers to more readily search for the roots of disease.

"What it does is accelerate discoveries of the basics of human disease," Reid said. "The Wellderly data set promises to offer a superior set of harmless variations, that will enable researchers to more effectively separate the harmless variations from the disease-causing variations."

Cheaper Sequencing