Researchers funded by the National Institutes of Health have discovered how a defect in a single master gene disrupts the process by which several genes interact to create myelin, a fatty coating that covers nerve cells and increases the speed and reliability of their electrical signals
The discovery has implications for understanding disorders of myelin production. These disorders can affect the peripheral nervous system?the nerves outside the brain and spine.
These disorders are known collectively as peripheral neuropathies. Peripheral neuropathies can result in numbness, weakness, pain, and impaired movement. They include one of the most common genetically inherited disorders, Charcot-Marie-Tooth disease, which causes progressive muscle weakening.
The myelin sheath that surrounds a nerve cell is analogous to the insulating material that coats an electrical cord or wire, keeping nerve impulses from dissipating, allowing them to travel farther and faster along the length of the nerve cell.
The researchers discovered how a defect in just one copy of the gene, known as early growth response gene 2 (EGR2) affects the normal copy of the gene as well as the functioning of other genes, resulting in peripheral neuropathy.
“The researchers have deciphered a key sequence essential to the assembly of myelin,” said Duane Alexander, M.D., Director of the NICHD, the NIH institute that funded the study. “Their discovery will provide important insight into the origins of disorders affecting myelin production.”
The study appears in the online version of Molecular and Cellular Biology.
John Svaren, Ph.D., an associate professor in the Department of Comparative Bioscience at the University of Wisconsin?Madison’s School of Veterinary Medicine, worked with colleagues Scott E. LeBlanc, and Rebecca M. Ward, to conduct the study. Dr. Svaren is an affiliate of NICHD-funded mental retardation and developmental disabilities research center at the Waisman Center at the University of Wisconsin.
Until this discovery, researchers did not fully understand the complex genetic process that enables Schwann cells, found in the peripheral nervous system, to coat nerves with myelin.