Synthetic Enzyme Therapy

MPS-1 occurs because the body is missing an enzyme that breaks down carbohydrates. Essentially, the cell's digestive system, which is called a lysosome, lacks an enzyme called Alpha-L-Iduronidase.

Without the enzyme, the cells cannot break down Mucopolysacchrides, which are long chains of sugar molecule, used in the building of connective tissues in the body.

The bodies of children with the disease are continually storing carbohydrates. These carbohydrates stick together and form a thick glue-like gelatin. Ligaments get very stiff and hands turn clawlike. Some internal organs also grow abnormally large. At one point, for example, Ryan Dant's liver and spleen were two and a half larger than normal.

Over a period of time, joints stiffen, valves of heart thicken, liver and spleen double in size. MPS-1 sufferers have splitting headaches, and can eventually go blind and deaf.

With Mike Dant's help, researchers developed a new therapy, known as enzyme replacement therapy. Researchers created a group of cells that reproduced the missing enzyme in the lab. This enzyme is then introduced into the body, via blood. Ryan Dant for instance, undergoes a 4-hour IV infusion every week.

The IV sends the missing enzyme throughout the body, allowing cells to process the carbohydrates. Since Ryan Dant began the therapy, he has improved enormously. He has grown eight inches, gained 50 pounds, and has almost no headaches. "He's a normal 8th grader," says his father, Mark Dant.

But there is still one problem to be solved: the synthetic enzyme does not cross the blood-brain barrier, which means that the carbohydrates still build up in the brain. This can lead to mental retardation. So Dant's organization has been funding research to solve this issue.

They are looking at two approaches. They are trying to perfect a gene therapy that would allow the body to create Alpha-L-Iduronidase, which would cross into the brain. They are also looking at "direct infusion," which send the enzyme directly to the brain.