Wednesday, 23 October 2019

Deaf Couple May Edit Embryo’s DNA to Correct Hearing Mutation

Image by Richard Wheeler/Creative Commons. United Kingdom, 2019.We sit at a corner table in an empty upstairs section of the restaurant while live Georgian music plays downstairs. Yevgenievna, in her late 20s, cannot hear it—or any music. She has been deaf since birth. But with the help of a hearing aid that’s linked to a wireless microphone, which she places on the table, she can hear some sounds, and she is adept at reading lips. She speaks to me primarily in Russian, through a translator, but she is also conversant in English.

Yevgenievna and her husband, who is partially deaf, want to have children who will not inherit hearing problems. There is nothing illicit about our discussion: Russia has no clear regulations prohibiting Rebrikov’s plan to correct the deafness mutation in an in vitro fertilization (IVF) embryo. But Yevgenievna is uneasy about publicity. “We were told if we become the first couple to do this experiment we’ll become famous, and HBO already tried to reach me,” Yevgenievna says. “I don’t want to be well known like an actor and have people bother me.” She is also deeply ambivalent about the procedure itself, a pioneering and potentially risky use of the CRISPR genome editor.

The couple met on vk.com, a Russian Facebook of sorts, in a chat room for people who are hearing impaired. Her husband could hear until he was 15 years old, and still gets by with hearing aids. They have a daughter—Yevgenievna asks me not to reveal her age—who failed a hearing test at birth. Doctors initially believed it was likely a temporary problem produced by having a cesarean section, but 1 month later, her parents took her to a specialized hearing clinic. “We were told our daughter had zero hearing,” Yevgenievna says. “I was shocked, and we cried.”

Their daughter could have received a cochlear implant, an electronic device that uses surgically implanted electrodes to directly stimulate the auditory nerve. People with such implants can understand speech, but typically can’t hear music. But Yevgenievna and her husband weren’t interested in the device for their child because friends in the Russian deaf community had bad experiences with it—likely because they didn’t receive the proper rehabilitation after the surgery to deal with flood of new signals to the brain.

Later, they learned the cause of their daughter’s hearing loss was genetic. Testing showed she had the same mutation in both of her copies of a gene called GJB2. The mutation, known as 35delG, is one of the most common genetic causes of hearing loss. People homozygous for 35delG, like Yevgenievna’s daughter, will inevitably have hearing loss, albeit to varying degrees. At the time, neither parent had ever had their genes tested—or even thought they had inherited their hearing problems.

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