Leukemia-cluster children share gene variation

FALLON - Scientists from the Centers for Disease Control and Prevention revealed Wednesday that a gene variant was found in all childhood-leukemia cases from Fallon involved in a genetic study.

The center studied 13 genes in a three-year process. One gene, called SUOX, was discovered to have a variant. The gene instructs the body how to make the enzyme sulfate oxidase, which changes unsafe chemicals in the body into safe substances.

Genetic testing was the next step by the CDC after a childhood leukemia cluster was first reported in 2000 in Fallon. Three children have died since 17 children developed leukemia since 1997.

Of the 14 families of surviving leukemia children, 11 voluntarily underwent testing for the genetic study in 2003. All 11 were found to have the variant of SUOX. However, the results were also consistent among 40 percent of the control group, said Dr. Carol Ruben, chief of the CDC's Health Studies Branch.

She said the study could not have been done if control families had not volunteered to undergo testing. She said there were three to four control samples studied for each of the leukemia case samples.

She said the gene variant is a significant finding; however, it's only one piece to a very complex puzzle.

"It takes time," she said. "This is good, good science."

Genes carry codes or messages that determine the body's functions and how it develops. Nearly all human genes, 99.9 percent, are the same, according to information provided by the CDC. In rare cases, a variant is found in 0.1 percent of the genome.

Ruben said the next phase is for other agencies and scientists to take what the CDC has found and study biological samples on a larger scope. The results are considered a step closer to identifying one factor for leukemia.

According to the study, if the variation in the SUOX gene is an added risk factor, other factors must be present.

"This is one step. There is more testing that needs to be done," said Dr. Karen Steinberg, chief science officer for the CDC's coordinating center for health promotion. "This will not predict that someone will get leukemia."

Since genotypes are present at birth, they do not appear or change based on environment or illness, said Steinberg.

"Although chemotherapy can affect cells, it does not affect genes," she said. "Therefore, undergoing testing after treatment would not change the results."

Jeff Braccini, of Fallon, whose 8-year-old son, Jeremy, was diagnosed with leukemia in 2001, said he was pleased with the latest study.

Braccini is treasurer of Families in Search of Truth, which has secured $750,000 in federal funding for research projects.

"Any time we get sound science, I fully applaud it," Braccini said. "My goal now is to tie the CDC and what they have done into our grant process that we have going on."

Richard Jernee, of College Place, Wash., whose 10-year-old son, Adam, became the first child to die in the cluster in 2001, said CDC waited too long to do DNA testing.

"It should have been conducted right away," he said. "I certainly hope it can be used as a stepping stone to get to the truth."

Dr. Scott Masten, a scientist for the National Toxicology Program, said it will be interesting to read the entire study and see where research can go from here.

"It's an interesting finding," Masten said.

The program is currently studying the effects of tungsten on lab rats and mice.

Tungsten was nominated for study in 2002 by the CDC's National Center for Environmental Health after high levels of the heavy metal were found in urine samples of Fallon residents. At the time, little was known about the health effects caused from exposure to tungsten. The CDC has since found no association between tungsten, or any other environmental factor, and the leukemia cluster.

He said the CDC studied SUOX for a reason. In animal studies, tungsten is know to replace the metal molybdenum, which helps make the enzyme work in the SUOX gene.

"It can replace molybdenum because tungsten is very similar," Masten said. "Then you see reduced function of the enzyme."

In the case of Fallon, there could be gene/environment interaction, he said. This could give researchers a direction to pursue. Three elemental factors can now be explored: the combinations of the gene variant, the high levels of tungsten found in Fallon studies, and exposure to other chemicals introduced into the body that the gene would filter, he said.

"We find variants in genes all the time. Whether it affects function of the gene is unknown," he said. "The only way to figure it out is with more study."

• The Associated Press contributed to this report.