July 29, 2013
Whole genome sequencing: Service focuses on eye, kidney, heart and autoimmunity for first two years
The Genome Clinic launching in July, 2013 brings whole genome sequencing and individualized medicine to the bedside of children with hard-to-treat and rare diseases. It is the first such comprehensive genome clinic for children in the world.
“Offering whole genome sequencing to physicians who are caring for children with diseases for which there is no treatment is a big step into the future. We expect that the next phase of genetic medicine will see solutions in some diseases that are currently fatal,” says Dr. Ronald Cohn. With Dr. Stephen Scherer, he is Co-director of the Centre for Genetic Medicine, which initiated and sponsors the clinic.
Many clinicians and researchers already analyze the genetic variants that cause disorders in individual patients. These “gene panels” are pre-selected sequences of genes that help to pinpoint the specific genetic variants that cause disease in most cases. “But not all children fit the norm of a disease. With whole genome sequencing we can strive to understand the unique genetic variants in individual children, and potentially strive to find a treatment for an individual child,” says Dr. Cohn.
He is a leading researcher of muscle-wasting conditions and is also a Senior Head, Division of Clinical and Metabolic Genetics at SickKids as well as Associate Professor of Paediatrics at University of Toronto.
Dr. Cohn came to SickKids in 2012 from Johns Hopkins University and Children’s Center specifically for the opportunity to move genetic medicine forward in all of paediatric medicine.
Catalyst for more complete diagnoses
The patients who may benefit the most in the clinic’s first two years include those with kidney, eye, heart and rheumatological diseases. A major benefit is in bringing together clinicians from different areas to review a child together, says Dr. Cohn. “Sometimes we find that one stream of genetic errors is associated with two apparently separate conditions and diagnoses. The Genome Clinic is a catalyst for more comprehensive diagnostic work as well as cross-disciplinary treatment at the bedside.”
The need for whole genome sequencing is also prioritized in rare types of epilepsy and cancer, neuromuscular wasting disorders, and metabolic disorders. Many of these are so-called ‘orphan diseases’ that are fatal and for which there is no effective treatment. “The whole genome sequence will allow us – in a very few cases – to pinpoint treatment options for specific children now,” he says. They will also vastly expand our research platform for these rare conditions, contributing to this new research endeavour around the world.
Whole genome sequencing can also help in more common diseases, such as childhood leukemias, when standard treatment does not work. “With a whole genome sequence we are more likely to be able to match the child to the best treatment for that individual from the start,” says Dr. Cohn. “And we get all this information from a simple cheek swab or blood sample.”
The potential to analyze all 30,000 genes in an individual child has been made possible by the reduced cost of whole genome sequencing, which is coming down from several thousand dollars to about one thousand dollars. “It’s like the revolution of personal computers that we saw 20 years ago – when it’s affordable, that changes everything,” Dr. Cohn says.
While the whole genome sequence answers a specific question about a complex disorder, it also answers many other questions that were not asked.
It can reveal the individual’s lifetime risk for genetically based conditions, from vision problems, cardiovascular disease and some kinds of mental illness to Alzheimer’s disease and hundreds of other conditions. “Unfolding this picture of lifetime medical risks in a young child is completely new in history and in medical ethics and opens up new challenges that need to be addressed. For that reason I request our trainee physicians to go through the consent process,” he says. “I had mine done, and it was one of the most profound experiences of my life.”