Genetic testing provides key to treatment
It's time to write positively about genetic testing!
While genetic testing available online may have many faults, well-controlled, clinically determined and supported genetic testing can have immeasurable benefits. A story in today's Chicago Tribune describes one such case.
Lilly Jaffe, 6, who was diagnosed with Type 1 diabetes when she was 1 month old, "now has the freedom to be a normal, active child. She can go to sleepovers or play dates without mom coming along to do blood sugar tests and operate her [insulin] pump. She can eat snacks without counting carbohydrates or testing her blood. The Jaffes don't even keep insulin in the house anymore."
Graeme Bell, a professor of medicine and human genetics at the University of Chicago, is the one who suggested that Lilly get tested for a genetic mutation first identified by a research team led by a British researcher, Dr. Andrew Hattersley of Peninsula Medical School in Exeter.
In a study published in the New England Journal of Medicine, Hattersley and colleagues showed that nearly half of patients diagnosed with diabetes before the age of 6 months have a mutation in one of two critical genes that work together to form a channel, or valve, that regulates the flow of potassium ions in and out of insulin-producing cells.
Normally, as glucose from food builds up in the bloodstream, the channel is cut off, causing potassium to accumulate in the cells. That, in turn, triggers the opening of another channel, for calcium. As calcium ions flow into the cells, they respond by secreting insulin.
The mutation - thought to affect as many as one newborn out of 200,000 - causes the potassium channel to remain open regardless of blood sugar. As a result, insulin secretion is drastically reduced, to undetectable levels in Lilly's case.
Hattersley showed that sulfonylurea drugs--currently used to treat only Type 2 diabetes--help close the potassium channel when needed, allowing cells to respond to glucose levels and make insulin.
Lilly is the fourth person to be treated this way in the U.S. and one of fewer than 100 in the world. But researchers suspect about 2,000 people in the U.S. have her kind of Type 1 diabetes and could benefit if diagnosed and treated early in life.
Now, let's put the pieces of this success together:
- A researcher in England studies patients with diabetes diagnosed before 6 months of age and identifies a couple of "diabetes" genes
- The molecular basis for the mutation is identified
- A professor in Chicago, suggests treating patients with a particular genetic mutation, suggests treating the diabetes in a radically different way.
- A genetic test is developed and a patient, on testing, is found to have the genetic mutation
- The girl's physician, director of the Comprehensive Diabetes Center in Chicago, puts the girl in the hospital and begins giving her low doses of sulfonylurea while gradually reducing her insulin, adjusting the insulin level as successively larger doses of the oral drug take effect.
- Within 5 days, Lilly has a new, less-encumbered life.
O.K., there is a down side. Very, very few people are affected by this particular mutation. And there are many, many mutations out there. But, as research progresses and connections are made between genetic information, disease, and treatment, similar successes will continue to happen.
You can access the complete article at http://www.kansascity.com/mld/kansascity/news/breaking_news/15525781.htm
Marie Godfrey, PhD