Scientists said yesterday that they have identified the location of a prostate cancer gene that is passed from mothers to their sons.
"People associate inheriting prostate cancers from their fathers, and there are families where that mode of inheritance is a factor," said Dr. William Isaacs, a Johns Hopkins geneticist who co-directed an international research effort. "In this case, men inherit the gene from their mothers."
Women do not get prostate cancer, but the study confirms scientists' earlier suspicions that mothers are sometimes carriers. In such cases, the disease follows the same pattern of inheritance as Duchenne muscular dystrophy, hemophilia and other "X-linked" diseases.
The prostate cancer gene is the second in two years to be located by a team that includes scientists in the United States, Sweden and Finland. In both cases, the scientists have found the approximate, but not exact, location of the genes along particular chromosomes.
The first gene, localized two years ago, occurs on the first chromosome and can be inherited from the mother or father. The second is carried on the X chromosome, which males inherit from their mothers.
The researchers who studied more than 1,500 afflicted men from 360 families are led by scientists at the Johns Hopkins School of Medicine and the National Genome Research Institute.
Each year, about 300,000 cases of prostate cancer are diagnosed in the United States. About one-tenth are triggered by inherited genes -- the rest from genetic defects that occur during a man's lifetime. Together, the two hereditary genes might account for about 40 percent of the cases that run in families, or about 12,000 cases a year.
An account of the study appears in this week's Nature Genetics, a leading scientific journal.
"Mapping [the gene] brings us one step closer to understanding bTC the origins of prostate cancer, at least in some families," said Dr. Francis Collins, director of the National Genome Research Institute.
There are still no genetic tests for prostate cancer. Until such tests are devised, Isaacs said, men who have family histories of prostate cancer should get monitored often for signs of the disease.
Isaacs said the research team is working to develop tests and to learn how the genes trigger the disease.
Pub Date: 9/29/98