The map, published Thursday, identifies more than 1.5 million tiny genetic differences among 71 people, said the team at Perlegen Sciences Inc., a spinoff of Santa Clara, Calif.-based gene chip maker Affymetrix Inc.

It is enough to find some of the most common genetic variations involved in disease, said David Cox, Perlegen's chief scientific officer.

To make the map, Perlegen worked with researchers at the California Institute for Telecommunications and Information Technology at UC San Diego and the International Computer Science Institute at UC Berkeley.