Stanley M. Gartler, a molecular biologist and geneticist whose work in the 1960s provided pivotal evidence that cancer originates from a single mutated cell, died on May 25 at his home in Seattle. He was 102. His death was confirmed by his nephew, Dr. Richard Weiner.

Dr. Gartler joined the University of Washington’s genetics faculty in 1957 and maintained an active laboratory until 2007. His research helped confirm a long-standing hypothesis proposed by German zoologist Theodor Boveri that tumors arise from a single cell undergoing uncontrolled division, a concept that until then lacked definitive proof.

In collaboration with pathologist David Linder, Dr. Gartler studied benign uterine tumors, or fibroids, in Black women and utilized the genetics of X chromosome inactivation to trace the origin of these tumors. Females carry two X chromosomes, but one is randomly silenced in each cell early in development. By examining the gene G6PD on the X chromosome, which has variants commonly referred to as A and B, they found that normal uterine tissue contained a mix of both variants in roughly equal proportions. In contrast, tumor tissue exhibited only one variant, indicating it derived from a single progenitor cell. Their findings were published in 1965 in the journal Science.

That same year, Dr. Gartler made another significant discovery while analyzing permanent human cell lines—cultures crucial to medical research. He found that 18 supposedly distinct cell cultures shared an identical rare variant of the G6PD gene, primarily found in Black individuals. This revealed widespread contamination of many cell cultures by the HeLa cell line, the first human cells to survive and multiply indefinitely in laboratory conditions. The HeLa line originated from cervical cancer cells taken without consent from Henrietta Lacks, a Black woman who died in 1951.

Dr. Gartler’s research demonstrated that HeLa cells could easily contaminate other cell lines, undermining the validity of numerous studies. At a 1966 conference in Pennsylvania, he warned the scientific community that many experiments using contaminated cultures were “open to serious question,” recommending they be discarded. Initially met with skepticism, his findings eventually prompted widespread recognition of the problem and led to improved standards for cell line authentication and laboratory techniques.

Beyond cancer research, Dr. Gartler contributed to the understanding of human genetic variation. In a 1962 paper, he co-described a case involving a girl with two different colored eyes and mixed sexual characteristics, explained by the presence of cells with both XX and XY chromosomes, likely due to early fusion of twins. This work highlighted the complexity of human sex determination.

Born in Los Angeles on June 9, 1923, to Romanian immigrant parents, Dr. Gartler served in the U.S. Army Air Forces during World War II before completing his education in genetics. He earned his Ph.D. from the University of California, Berkeley, and completed postdoctoral work at Columbia University prior to his long tenure at the University of Washington.

Dr. Gartler was married to Marion Mitchelson Gartler, a writer and editor, who died in 2016. He had no immediate survivors. His work remains influential in cancer biology, genetics, and laboratory standards, underscoring the importance of rigorous scientific validation and ethical considerations in biomedical research.