I spent Memorial Day weekend riding in a lot of cabs in Philadelphia. All the cabs played the same endless loop of TV segments on those little screens in the backseats. So, in those backseats, I watched over and over again an NBC news segment about two little boys, Jonah and Dylan, who are best friends. Jonah has a disease called glycogen storage disease. Dylan wrote a book called “Chocolate Bar” to raise funds to help Jonah with his illness. If this story doesn’t tug at your heartstrings, I don’t know what will.
But I became curious about glycogen storage disease, or GSD, so once the weekend was over, I reached out to David Weinstein at the University of Florida. Weinstein is the director of the Glycogen Storage Disease Program, the largest research program into the disease in the United States.
Weinstein says he became aware of the disease’s devastation in 1998. “I was invited to speak at the national conference for people and families with GSD, and I was shocked by the poor state of health of this population,” he recalls. “There was almost no research occurring, and there was little hope for the families. At this conference, I decided that someone needed to care for these children, and I decided to build a program to help them.”
GSD comes in 16 different forms, some which affect the liver and some which affect muscle. The liver forms present themselves as hypoglycemia, and the muscle ones show up as muscular dystrophy. The young boy Jonah “has GSD Ib, which is one of the rarest forms, impacting about one in 1 million children,” explains Weinstein.
GSD Ib is an autosomal recessive disorder. The defect in GSD Ib is found in the glucose-6-phosphate transporter, which is needed for glucose to be released from the liver between meals. The transporter sits in the endoplasmic reticulum and moves glucose-6-phosphate from the cytoplasm into the interior of the ER. There, the glucose-6-phosphate gets turned into glucose in the final stages of gluconeogenesis and glycogenolysis.
But in people like Jonah, the glucose-6-phosphate transporter is missing so glucose can’t be generated. Weinstein adds that almost all children with GSD Ib develop inflammatory bowel disease and a condition called neutropenia, which is a low count of white blood cells.
The symptoms of GSD present themselves in children with nebulous, indistinct ways, such as poor growth, abdominal distention and developmental delay. These symptoms are nonspecific, so diagnosis often is missed for several months.
The current treatment for GSD Ib is something found in grocery stores: cornstarch. Cornstarch is degraded by the body at a rate similar to the basal metabolic rate of the body. So it meets the energy needs of the body without having to store the carbohydrate. Until the cornstarch therapy was discovered in 1971, the disease used to be fatal.
But it isn’t the optimal treatment. It works, says Weinstein, but the neutropenia still requires daily injections and gastrointestinal issues persist. A new type of cornstarch did get released last year. It breaks down over a longer period of time, which has helped many children with GSD, says Weinstein. He says his group is in the process in applying for permission from the U.S. Food and Drug Administration to perform gene therapy for GSD Ia, a related condition.
Weinstein says because GSD, especially GSD Ib, is so rare, there is not much known about the disease and research into its diagnosis and treatments is neglected. “With less than 100 children in the United States with GSD Ib, few doctors have seen it,” Weinstein states. “This subtype is often not mentioned in medical schools, and the GSDs as a whole usually receive less than 30 minutes of time when medical students are training.”
According to Weinstein, there isn’t any support from the National Institutes of Health or a foundation. “The book, ‘Chocolate Bar,’ has raised more money for research than all medical foundation and grants combined.” So far the book has raised $275,000 with the goal of reaching $1 million.
