Another genetic change linked to neuroblastoma: missing DNA
(4 July 2009: VIDYYA MEDICAL NEWS SERVICE) -- A series of genome studies have, for the first time, revealed common genetic changes associated with neuroblastoma, a cancer that most often occurs in children. Building on this work, researchers have now expanded the scope of these surveys to include structural changes, such as gains and losses of DNA. As reported in the June 18 Nature, this strategy has revealed a region of chromosome 1 that is missing in some children with neuroblastoma and that may contribute to their disease.
Gains and losses of DNA, known as copy number variations or CNVs, have been linked to conditions such as autism and schizophrenia, but this study is the first to demonstrate their role in predisposing to cancer. Dr. John Maris of the Children’s Hospital of Philadelphia and his colleagues made the discovery by screening DNA from 1,600 children with and without the disease. The missing DNA on chromosome 1 was confirmed in two independent groups, and additional evidence for its role in neuroblastoma came from experiments in cells.
Neuroblastoma arises in children in the developing cells of the sympathetic nervous system. The unstable region of chromosome 1 is near a family of genes involved in the development of the central nervous system. In experiments with cells, the researchers learned that the CNV alters the activity of a previously unknown member of this gene family, which resides within the region. The presence of this CNV alone is not sufficient to cause neuroblastoma, the researchers noted.
Indeed, a variety of genetic alterations contribute to the disease, including, it now appears, CNVs. In their previous studies (here, here, and here), Dr. Maris and his colleagues in the Children’s Oncology Group implicated two other types of genetic changes—mutations and single nucleotide polymorphisms (SNPs), which are places in the genome where a single letter of DNA may vary from person to person.
“It has been widely thought that CNVs could play a role in cancer, but the evidence has been lacking,” said Dr. Sharon Diskin of the Children’s Hospital of Philadelphia, the first author of the new study. “We hope that our findings provide the evidence for the importance of expanding genome-wide association studies to include CNVs as well as SNPs in cancer.”
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