It may open a new era in the ever-disappointing effort to identify the genetic roots of fatal disease like heart attacks, diabetes and Alzheimer's, the reports said.

    In the decade since the first full genetic code of a human was sequenced for about 500 million U.S. dollars, less than a dozen genomes have been decoded, all of healthy people.

    Geneticists said the new researches show it is now possible to sequence the entire genome of a patient at reasonable cost of just 50,000 dollars one subject with sufficient accuracy to be of practical medical use.

    "This is the first time whole genome sequencing has applied to actually find the cause of a disease," one of the researchers said.

    Several cases are analyzed in the two reserches. In one case, Richard A. Gibbs of the Baylor College of Medicine sequenced the whole genome of his colleague Dr. James R. Lupski, a prominent medical geneticist who has a nerve disease, Charcot-Marie-Tooth neuropathy.

    In another, Leroy Hood and David J. Galas of the Institute for Systems Biology in Seattle decoded the genomes of two children with two rare genetic diseases, and their parents.

    Besides identifying disease genes, the second team was able to make the first direct estimate of the number of mutations, or changes in DNA, that are passed on from parent to child.

    They calculate that of the three billion units in the human genome, 60 per generation are changed by random mutation -- considerably less than previously thought.