Genetic Clue to Painful Peripheral Neuropathy

June 22, 2011 -- A single gene may be responsible for the pain suffered in many people diagnosed with a type of peripheral neuropathy that previously had no known cause, a study shows.

The discovery could lead to effective treatments for the disorder, which is often characterized by burning, tingling, and numbness in the hands and feet.

The study is published in the Annals of Neurology.

Peripheral nerves are any nerves located outside the spine or brain. Damage to them -- whether by injury, infection, diabetes, or other cause -- results in peripheral neuropathy.

Treating the underlying cause of peripheral neuropathy often relieves the pain. However, for nearly a third of those diagnosed with the disorder, no such underlying cause can be identified, which greatly limits treatment options.

"For millions of people, the origin of this intense pain has been a frustrating mystery," co-researcher Stephen Waxman, MD, PhD, a professor of neurobiology and of pharmacology at Yale University, says in a news release.

'Mystery' Cases of Peripheral Neuropathy

Now, though, Waxman and his fellow researchers at Yale, the Veterans Affairs Medical Center in West Haven, and the University Maastricht in the Netherlands believe they have found a genetic mutation that may account for as many as 30% of these mystery cases, known as idiopathic small nerve fiber neuropathy.

Twenty-eight Dutch patients were recruited for the study after being screened for any possible known causes of the disorder. Genetic analysis revealed that eight of these men had mutations in the SCN9A gene, which, the study notes, has been associated with other pain-causing disorders.

Further analysis showed that the mutation triggered hyperactivity in certain neurons, possibly leading to nerve degeneration and subsequent development of neuropathy.

"These findings will help us as clinicians to a better understanding of our patients with small fiber neuropathy and could ideally have implications for the development of future specific therapies," University Maastricht neurologist Catharina G. Faber, MD, PhD, one of study researchers, says in a news release.