MONDAY, Jan. 28, 2019 (HealthDay News) --Recent advances in gene therapy may eventually lead to a cure for sickle cell disease.

The disease is caused by a single mutation in one gene and mainly occurs in people of African descent. About 100,000 people in the United States have the disease, which causes agonizing pain, strokes and early death, The New York Times reported.

Currently, the only treatment is a risky and costly bone marrow transplant.

In a half-dozen clinical trials planned or underway, researchers are testing genetic therapies for sickle cell disease and some patients in those studies no longer have signs of the disease

One of those patients is 21-year-old Brandon Williams of Chicago, who had four strokes by age 18. His older sister died of the disease. After experimental gene therapy, he no longer has symptoms of sickle cell disease, The Times reported.

Despite promising results, it's unclear if the effects of treatment will last and it's likely to be at least three years before a genetic therapy for sickle cell disease is approved.

"We are in uncharted territory," Dr. David A. Williams, chief scientific officer at Boston Children's Hospital, told The Times.

"This would be the first genetic cure of a common genetic disease," Dr. Edward Benz, professor of medicine at Harvard Medical School, told The Times.