Glycogen storage disease could affect 1 in 500 Nunavik Inuit

A medical mystery that could have implications for Nunavik residents has been solved by researchers, 15 years after five Inuit children were found to have enlarged livers.

In a study published last week in the Canadian Medical Association Journal, Canadian and Japanese researchers identified a genetic mutation in Inuit responsible for glycogen storage disease type IIIa.

Researchers conservatively estimate that one in 2,500 Nunavik residents may have the disease, but Dr. Celia Rodd, who worked on the study, says it's "probably closer to one in 500."

Glycogen storage disease stops the body from being able to properly process its sugar reserves, stored in the liver as glycogen. It results in an enlarged liver, muscle weakness, and low blood sugar levels.

The possibility of glycogen storage disease was first suggested when multiple Inuit children from Nunavik with similar symptoms were examined by Dr. Rodd, then in Montreal.

"They were coming in with a big belly, they had weak muscles, and they also had low blood sugar," said Dr. Rodd, who is now based at Winnipeg's University of Manitoba. "We thought they looked just like children that had glycogen storage disease."

"The families came to us and said: 'why do our children have this?' And we started to run some genetic tests. But going back 15 years ago... finding out the specific change in the gene that makes this, we couldn't find it at that time."

The genetic mutation was eventually uncovered by Dr. Rodd's team in Winnipeg, as well as researchers at Montreal's McGill University and the Okinawa Memorial Institute for Medical Research in Tokyo, Japan. It had previously been found in North African patients, but never in North American children.

"The children that have glycogen storage disease are healthy children," says Rodd. "They go out, they go to school, and they do all those activities. But it can be very damaging to their liver and to their heart."

Rodd says that now that the gene has been identified, Nunavik communities can do specific screenings for newborn children, identifying the disease before any problems begin to manifest. People affected by glycogen storage disease can live healthy lives if the disease is treated properly, by regularly testing blood sugar levels, adhering to a proper eating schedule, and having their liver checked frequently.