Unverricht-Lundborg disease is a rare inherited form of epilepsy. Affected individuals usually begin showing signs and symptoms of the disorder between the ages of 6 and 15.

Mutations in the CSTB gene cause Unverricht-Lundborg disease. The CSTB gene provides instructions for making a protein called cystatin B. This protein reduces the activity of enzymes called cathepsins. Cathepsins help break down certain proteins in the lysosomes (compartments in the cell that digest and recycle materials). While the specific function of cystatin B is unclear, it may help protect the cells' proteins from cathepsins that leak out of the lysosomes.

Progressive myoclonus epilepsy is a rare condition. Unverricht-Lundborg disease is believed to be the most common cause of this type of epilepsy, but its worldwide prevalence is unknown. Unverricht-Lundborg disease occurs most frequently in Finland, where approximately 4 in 100,000 people are affected.

This condition is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition.

Published Date: June 01, 2008Published By: National Institutes of Health