Jordan Janz used to take 40 to 60 pills every day to treat a rare genetic disease. But a side effect of the medicine made the 22-year-old smell bad.

Janz is now taking an experimental gene treatment. He thought the treatment might be worth it when he went to work and his friend said he smelled good.

"And I'm like, ‘that's probably the nicest thing you've ever said,'" Janz remembered.

Janz was born with a damaged gene that made him unable to make a protein needed by many organs in the body. Children with the disease, called cystinosis, can vomit many times a day. They may need medicine for their eyes every hour to avoid losing their sight. Many also need kidney transplants before they are adults.

Now, Janz and others with rare diseases are hopeful about genetic treatments. Gene therapy is now being used to fight disease by supplying the DNA patients lack.

Janz was the first person in a study of the treatment at the University of California, San Diego. He and two other patients with the same disease no longer need eye drops or pills. The company that developed the treatment is testing it for several other diseases by changing the target gene.

Dr. Peter Marks is the head of the U.S. Food and Drug Administration center that deals with gene treatments. He said if one method for gene therapy can be found to be safe it can then be adapted for many different uses.

Not so rare

In the United States, a disease is considered rare if it affects fewer than 200,000 people. There are more than 7,000 rare diseases that are believed to affect a total of 30 million Americans.

Seven kinds of gene therapies are approved in the United States. At the end of 2020, 1,085 companies were developing treatments. More than 400 gene therapy tests are being carried out.

Ron Bartek is with the National Organization for Rare Disorders. He said there have been many developments in recent years. He added, "We're finally looking at the possibility of profoundly beneficial therapies" for many diseases.

Changing DNA

Gene therapies aim to supply a gene to patients who are missing one. The goal is to get the new gene where it needs to be without creating other problems.

Some therapies, like ones for genetic blindness, inject the treatment into the eye. Some treatments remove some of a patient's blood cells. The cells are then changed to carry the gene and returned to the patient.

Another therapy puts genes inside disabled viruses. One treatment uses HIV, the virus that causes AIDS. Orchard Therapeutics in London is one company that has used this method. The company said its gene therapy using the HIV virus gave a working immune system to 48 babies who were born without one.

Difficulties remain

Gene therapy does not work for all patients. It remains unclear how long it lasts, and there are safety concerns. Some gene therapies have caused cancer in a few patients.

The FDA's Peter Marks said safety issues remain a concern. He and many other scientists think gene editing may one day provide a long-lasting answer for gene therapy. Instead of supplying a missing gene to cells, gene editing permanently changes DNA.

‘I have more of a life'

Janz was treated in 2019 and said he feels "cured." But it will take years to know if he actually is. He may still need a kidney transplant someday because of damage done by the disease.

People with cystinosis like Janz are unable to remove cystine, a chemical that builds up in cells. Cystine forms hard structures, called crystals, which damage the kidneys, eyes and other organs. Its effects can lead to muscle weakness and trouble breathing.

Tests show that the crystals in Janz's eyes, skin and muscles have greatly decreased. Instead of 54 pills a day, he takes vitamins and other nutrients.

"I have more of a life now," Janz said. "I'm going to school. I'm hoping to open up my own business [some] day."

I'm Caty Weaver.

Marilynn Marchione reported this story for The Associated Press. Dan Novak adapted it for VOA Learning English. Mario Ritter, Jr. was the editor.

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pill –n. a small round object that contains medicine or nutrients that is swallowed

vomit –v. to have what is in your stomach come out of your mouth because you are sick

transplant—v. to perform a medical operation in which an organ or other part that has been removed from the body of one person is put into the body of another person

therapy — n. the treatment of physical or mental illnesses

adapt — v. to change (something) so that it functions better or is better suited for a purpose

profound — adj. very strongly felt

benefit — n. a good or helpful result or effect

disable — v. to cause (something) to be unable to work in the normal way

immune system — n. the system that protects your body from diseases and infections