Genic mutation found to be the cause of rare disease

A 30-year-old Shanghai patient Yanzi has suffered inherited rare disease for 10 years. Her parents are tested to be heterozygous mutation carriers.

DOCTORS who have been treating a Shanghai woman suffering from a rare disease for the last 10 years say gene mutation is the cause of the disease.

The 30-year-old woman, identified as Yanzi, has been battling the disease since the age of 20. She would show symptoms similar to neurotic convulsion or electric shock.

According to her parents, she suffers from it once every one-and-half-months. It lasts for 15 or 16 days.

Doctors have diagnosed the disease as epilepsy, progressive myoclonic 4 (EPM4) — the fifth such case in China. But the cause of the disease remained unclear until Yanzi and her parents received a molecular genetic test this month.

Ruijin Hospital said yesterday that the test results showed that Yanzi’s parents were heterozygous carriers. But the mutation did not occur among the parents, but there was a 25 percent possibility that their offspring could be affected by it.

Yanzi can no longer walk and has lost the linguistic ability after suffering the disease for a decade. She can only communicate with others with eye contact and rambles through in her conversations even though she remains conscious.

There is no effective therapy for EPM4. A neurosurgery would not help either, experts at Ruijin Hospital said. Doctors can only give pertinent treatments to her symptoms, and suggest changes in nutrition to avoid complications.

According to Cao Li, deputy director of the hospital’s neurology department, even though Yanzi’s parents did not have a consanguineous marriage, their ancestral homes — Yanzi’s father and maternal grandfather — are from the same region. Cao says it is possible that is why both Yanzi’s parents are carriers of the rare disease.

Diseases with incidence of lower than one in 500,000, and lower than one in 10,000 in newborns are considered rare diseases. There are about 7,000 known rare diseases in the world. Only a few of them have established medical treatment. China has about 16 million rare disease patients. Such rare disease are rarely tested in prenatal examinations.