Sickle cell cure brings a mixture of fear and hope

But she has other concerns, particularly for her 7- and 12-year-old daughters. The lengthy hospitalization for gene therapy, followed by months of recovery, would be tough on her, she said.

“They’re not babies, but they need me,” Ms. Polanco said.

Patients ask when in the course of the disease gene therapy is necessary. If they wait too long, the disease can lead to a stroke or permanent damage to organs and bones. But if the disease is mild and manageable, is it better to wait? André Marcel Harris, 33, who lives in Houston, decided waiting was his best option.

“I’m not as ill as many others,” he said. “At this point, gene therapy is not part of the conversation.”

Shamar Lewis, 20, who lives in Orlando, Fla., has several concerns – potential long-term side effects of gene therapy, cost, and the months-long process of treatment and recovery.

Still, the sickle cell was such a burden. He spent years of early adolescence unable to go to school because he was so ill – his school even sent teachers to his home. He has now graduated from high school and is interested in military service, but has since learned that with sickle cell disease he would not be accepted. With gene therapy, “I would be able to really live my life,” he told his mother, Carla Lewis.

But what would that life be like?

Without the disease, said Teonna Woolford, 31, a sickle cell patient and advocate who lives in Owings Mills, Md., “patients don’t know who they are.” Many worry, she said, “of trading a known problem — sickle cells — for something different and a general fear of the unknown.”