loss Noun
But he did not know which gene or genes had disappeared .
Then , a scientific team led by molecular geneticist Webster Cavenee , then at the University of Utah , found the answer .
The team used a battery of the newly developed “ gene probes , “ snippets of genetic material that can track a gene 's presence in a cell .
By analyzing cells extracted from eye tumors , they found defects in the second copy of chromosome 13 in the exact area as in the first copy of the chromosome .
The finding riveted medicine .
It was the first time anyone had showed that the loss of both copies of the same gene could lead to the eruption of a cancer .
“ It was extraordinarily satisfying , “ says Dr. Knudson , now at Fox Chase Cancer Research Center in Philadelphia .
“ I was convinced that what was true of retinoblastoma would be true for all cancers . “