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Everything appears normal during childhood and adolescence. But in young adulthood, a gradual deterioration of the muscles suddenly sets in. After another ten to 20 years, a wheelchair is required and with it comes a lower life expectancy. An international research consortium is examining why this happens to patients with the rare disease GNE myopathy. Also involved in this alliance is a team led by Professor Rüdiger Horstkorte from the Institute of Physiological Chemistry (IPC) at the Faculty of Medicine of University Medicine Halle (Saale). As the national project sponsor, the German Research Foundation (DFG) has pledged 360,000 euros to fund the work within the alliance over a three-year period.

In 2000, scientists in Jerusalem (Israel) discovered that the rare disease is caused by a genetic defect in an enzyme that, in healthy people, produces sialic acid. The sugar is essential for the cells’ molecular framework and ensures they can recognize each other. The defect causes major sialic acid deficiency in those affected by GNE myopathy.

The disease occurs when both parents are carriers of the genetic defect. “We don't know why this disease only appears after the age of 20 and why only the muscles are affected. As the disease progresses, there is a gradual breakdown of all of the patient’s muscles. Only the thigh muscle does not appear to be affected, and here, too, we don’t know why this is the case,” says Professor Rüdiger Horstkorte from the IPC, who studied sialic acid as part of his post-doctoral degree and is one of a handful of experts worldwide.

GNE myopathy affects about five to ten thousand people worldwide, most notably in the Middle East, the USA and Japan. The initiator of the joint project is an Italian scientist who is herself affected by the disease and who brought together several research groups from Europe and Canada for the EU project proposal to study the disease. “The idea of the consortium is to mimic the disease in cell cultures and treat it with sugars. We in Halle are best placed to demonstrate that the sugar arrives in the structures on the surface and does what it is supposed to do there. The plan is for us to become a reference laboratory for research into GNE myopathy. Nothing like this currently exists and we would be the first in the world,” explains Horstkorte.

Sialic acid and its precursors can be produced cheaply in large quantities. The research project is also examining how the sugar can be introduced into the cells because it is difficult to administer orally in humans. “The sugar can be easily ingested, but large quantities of it would be required per day because it is not absorbed well by muscle cells. Once we have found a better way that works in cell cultures, it will be tested on those affected by the disease,” says Professor Horstkorte. Patients are already lining up to participate and even donate muscle samples. “The joint EU project aims to find an inexpensive and safe way to help those affected. Otherwise, the only option would be gene therapy, which is not without its risks and is socially controversial,” says Horstkorte.