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Missing DNA could cause neuroblastoma


The study is the first to show that repeats or deletions of a genetic sequence influence cancer risk (Source: iStockphoto)


The study, which appears in Nature, is the first to show that repeats or deletions of a genetic sequence, as opposed to 'spelling mistakes' in the four-letter genetic code, influence cancer risk.

Hundreds of studies show that inherited genetic variations called single-nucleotide polymorphisms, or SNPs, play a role in the development of cancer. These are one-letter changes in the genetic code.

"This is the first paper to really show that copy number variation, which is just another mechanism of evolution for why you and I are different, can be involved in predisposition of cancer," says Dr John Maris of the Children's Hospital of Philadelphia.

Maris and colleagues also identified an entirely new gene, neuroblastoma breakpoint family 23 or NBPF23, which plays a role in neuroblastoma. It is part of a family that was previously associated with the cancer, he says.

Mystery unlocked

The research adds to a growing understanding of the genetic causes of neuroblastoma, a cancer affecting developing nerve tissue that accounts for 15% of all cancer deaths in children.

Last year, Maris identified three genes that affect the risk of aggressive neuroblastoma.

"Only two years ago, we had very little idea of what causes neuroblastoma," says Maris. "Now we have unlocked a lot of the mystery of why neuroblastoma arises in some children and not others."

His team scanned the genetic code of 846 children with neuroblastoma and 803 seemingly healthy children. They found that children who were missing a stretch of genetic code on chromosome 1, which is especially important for nerve development, are predisposed to develop the cancer.

"What our paper shows is that if you have copy number variations on chromosome 1, you are more likely to develop neuroblastoma," says Maris.

Maris suspects copy number variation plays a role in how much of the NBPF23 gene is produced.

"It will take future study to understand whether or not it leads to a more aggressive or less aggressive form of the disease," he says.

Maris suspects copy number variation will be found to play a role in other cancers.

He hopes the findings will lead to more targeted treatments for neuroblastoma.

Tags: cancer, biotechnology, cloning-and-dna, genetics, genetic-disorders