25 December, 2017
American health officials recently approved the first gene therapy treatment for an inherited disease – the type that can pass from parent to child.
The treatment improves the sight of patients suffering from a genetic mutation that destroys their ability to see. It is the first gene therapy approved where a corrective gene is given directly to patients.
People with the disease usually start losing their sight before they are 18. This often progresses to total blindness. The gene that causes the disease could suddenly appear when a child is born with a copy of the gene from both parents.
Only a few thousand people in the U.S. are thought to have the condition.
Patients receive the therapy, called Luxturna, through two injections, one for each eye. These replace the problem gene that prevents the retina, a tissue at the back of the eye, from changing light into electronic signals sent to the brain.
Mistie Lovelace received one of the early treatments. She said, "One of the best things I've ever seen since surgery are the stars. I never knew that they were little dots that twinkled."
Drugmaker Spark Therapeutics has not set the price for the treatment. Its own research, however, has put the value of the therapy at around $1 million.
The company says the reason for the high price is due to their prediction that Luxturna will be given only once, with lasting positive effects. To date, the company has researched patients in a study for as long as four years and has not seen their vision worsen.
The Food and Drug Administration has approved three gene therapies since August. The two other treatments are specially designed treatments for forms of blood cancer.
New success for difficult field
The approval marks an important growth for a field of study that has struggled with safety concerns.
In 1999, a patient treated for a rare metabolic disorder at the University of Pennsylvania died. In another case, patients treated for an immune disorder later developed leukemia.
Dr. David Valle said the excitement about the possibilities for genetic medicine create opportunities for research on individual diseases.
University of Pennsylvania researcher Dr. Jean Bennett said she and her husband, Dr. Albert Maguire, first imagined using genetic medicine to treat retinal blindness in the mid-1980s.
But it took many years to develop the science and technology. The first animal tests happened in 2000 and the first human tests in 2007.
"We didn't know what genes caused the disease, we didn't have animal models with those genes, we didn't have the ability to clone genes and deliver them to the retina — so it took time to develop all that," said Bennett.
I'm Phil Dierking.
Matthew Perrone reported this story for the Associated Press. Phil Dierking adapted this story for VOA Learning English. Hai Do was the editor.
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Words in This Story
clone - n. a plant or animal that is grown from one cell of its parent and that has exactly the same genes as its parent
dots - n. small round marks
gene therapy - n. a way of treating some disorders and diseases that usually involves replacing bad copies of genes with other genes
immune - adj. not capable of being affected by a disease
inherit - v. to have (a characteristic, disease, etc.) because of the genes that you get from your parents when you are born
leukemia - n. a very serious disease in which the body forms too many white blood cells
metabolic - adj. the chemical processes by which a plant or an animal uses food, water, etc., to grow and heal and to make energy
mutation - n. a change in the genes of a plant or animal that causes physical characteristics that are different from what is normal
surgery - n. medical treatment in which a doctor cuts into someone's body in order to repair or remove damaged or diseased parts
twinkle - v. a quick, unsteady movement of light
opportunity - n. an amount of time or a situation in which something can be done
deliver - v. to take (something) to a person or place