In 1967, Gartler was interested in establishing a system for studying human genetics in somatic cell culture. He initially collected eighteen (supposedly) independently derived established human cell lines, including HeLa. Examining isoenzymes, he typed them for a number of genetic polymorphisms, including the X linked G6PD variant. The cell lines turned out to be genetically identical, and further, all carried the G6PD allele found almost exclusively in people of African descent. HeLa, the first successfully established human cell line, was derived from a woman of African descent named Henrietta Lacks, so this result suggested that the cell lines were not truly independent, but had been contaminated by HeLa cells.