U.S. geneticists say they have found evidence a category of genes, known as pseudogenes, serve no function -- a finding supporting the theory of evolution.

There are approximately 20,000 pseudogenes in the human and other mammalian genomes. In recent years, there's been growing discussion about pseudogenes -- the issue centering on whether pseudogenes are functional or just evolutionary relics with no function.

It was long believed by geneticists they were relics, until research published in 2003 found a mouse pseudogene that did have a function, namely to cause polycystic kidney disease and a bone disease known as osteogenesis imperfecta. That finding was hailed by proponents of the theory of intelligent design as proof of their belief.

But the new research at the Children's Hospital of Pittsburgh and the Wadsworth Center in New York finds scientific evidence that contradicts the previous finding.

The new study's senior author, Robert Nicholls, said the pseudogene in question is not the cause of those diseases. Instead, it merely is an inactive copy of a gene -- an evolutionary relic as previously believed.

Results of this study are detailed in the Aug. 8 issue of the Proceedings of the National Academy of Sciences.

Copyright 2006 by United Press International