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Secrets of Childhood Cancer

June 22, 2009

Two new studies from The Children’s Hospital of Philadelphia advance the search for genetic events that result in neuroblastoma, a puzzling, often deadly type of childhood cancer.

Originating in the peripheral nervous system, neuroblastoma is the most common solid cancer of early childhood and causes 15 percent of all childhood cancer deaths. “Only two years ago we had very little idea of what causes neuroblastoma,” study leader John M. Maris, M.D., chief of Oncology and director of the Cancer Center at The Children’s Hospital of Philadelphia is quoted as saying. “Now we have unlocked a lot of the mystery of why neuroblastoma arises in some children and not in others.”

In the largest gene study to date in pediatric oncology, Maris’s study team performed a genome-wide association study to discover that common variants in the gene BARD1 increase a child’s susceptibility to a high-risk form of neuroblastoma.

A second genome-wide study found that a copy number variation (CNV)””a missing stretch of DNA””along a structurally weak location on chromosome 1 plays an important role in the development of neuroblastoma.

The researchers made use of highly automated gene-analyzing technology at the Center for Applied Genomics at Children’s Hospital of Philadelphia, directed by Hakon Hakonarson, M.D., Ph.D., a co-author of both studies. They used specimens collected from around the world through the Children’s Oncology Group.

The BARD1 gene had already attracted attention from oncology researchers because it is associated with the gene BRCA1, which was the first discovered familial breast cancer gene. “Researchers have suspected that variants in BARD1 also increased the risk of breast cancer, but no one has found compelling evidence of this,” said Maris. “Instead, surprisingly, our genome-wide association studies found that BARD1 is a susceptibility gene for neuroblastoma, and perhaps other cancers as well.”

Maris’s second study, spearheaded by Dr. Sharon Diskin, also of The Children’s Hospital of Philadelphia, found that an inherited CNV located at chromosome 1q21.1 is associated with neuroblastoma. The chromosome region contains a large family of genes that are involved in the development of the nervous system, and the CNV they discovered changes how much of one particular gene is made within normal nerve and neuroblastoma cells.

As gene studies continue to better define the genetic landscape of neuroblastoma, added Maris, pediatric oncologists can develop more precise targeted treatments to improve survival and quality of life for children with this complex disease.

SOURCE: Nature Genetics, May 3, 2009, and Nature, June 17, 2009




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