By Admin at 11 Jan 2016, 12:32 PM

Comprehensive genetic testing may be offered for pediatric cancer patients who have a family history of cancer. However, new research suggests hereditary genetic mutations that predispose a child to cancer may be present even in children with no family history of the disease.

Researchers from the St. Jude Children's Research Hospital, Washington University Pediatric Cancer Genome Project, conducted DNA sequencing on more than 1,100 children with cancer.

A sizable portion – 8.5 percent – had germline mutations in cancer-predisposing genes. The researchers suspect this percentage may grow as more is understood about such mutations in young cancer patients.

Germline mutations, also known as hereditary mutations, are those that are passed down from parents to children. Surprisingly, among the children with the hereditary mutations, only 40 percent had a family history of cancer.

Study co-author Richard K. Wilson, Ph.D., director of the McDonnell Genome Institute at Washington University School of Medicine in St. Louis, told Medical Xpress:

"We've suspected for some time that many pediatric cancers could be traced to an inherited genetic predisposition. Now, using genome sequencing, we can see the contribution of germline mutations to pediatric cancer risk.

Our results explain why children, who have not lived long enough to accumulate a critical number of cancer-causing mutations, can still develop cancer."

The research suggests that all pediatric cancer patients, even those without a family history of cancer, may benefit from comprehensive genetic screening.

Such testing may help with cancer detection and treatment, as well as genetic screening recommendations for patients’ parents and siblings. The study also revealed a number of surprising findings, including:

• Mutations in BRCA1 and BRCA2 (breast and ovarian cancer genes) were among the most commonly mutated genes detected; these genes are not currently included in genetic screening for pediatric cancer patients as they’re typically associated with adult-onset cancers
  
  
• Germline mutations were discovered in six patients with Ewing sarcoma, a bone and soft tissue cancer that was not thought to be a hereditary cancer

St. Jude has begun a new research study, Genomes for Kids (G4K), which will test new pediatric cancer patients being treated at the hospital for germline mutations.

Those found to have a germline mutation in a cancer predisposition gene will be referred to the new St. Jude Hereditary Cancer Predisposition Clinic, one of the only such clinics in the world that’s working with children and families that may have an elevated predisposition for cancer.

For now researchers are still determining how to interpret their findings. For instance, if a sibling has the same germline mutation as the cancer patient, what is the likelihood that they, too, will develop cancer? It’s an unanswered question for now, but ultimately the hope is that such screenings will pave the way for earlier detection and more targeted treatment.

Sources:
New England Journal of Medicine December 10, 2015
Medical Xpress November 18, 2015

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