Distillations: The Death of Jesse Gelsinger, 20 Years Later
Gene editing promises to revolutionize medicine. But how safe is safe enough for the patients testing these therapies?
By all accounts Jesse Gelsinger was a sweet, sharp-witted, if not particularly ambitious kid who loved motorcycles and professional wrestling. In 1999 he was living in Tucson, Arizona, with his parents and siblings, attending high school, and working part-time as a supermarket clerk. As he got older, he became more independent and, like many teens, a touch rebellious; in his case that led to life-threatening health problems.
Jesse had a rare metabolic disorder called ornithine transcarbamylase deficiency syndrome, or OTCD, in which ammonia builds up to lethal levels in the blood. Babies born with OTCD usually fall into comas soon after birth and suffer brain damage. Half of them die within a month. Jesse’s milder version of the deficiency was diagnosed when he was two years old, and he managed the condition with a low-protein diet and a regimen of nearly 50 pills a day.
Still, he had occasional health crises. When he was 17, he stopped taking the drugs regularly. One day his father came home to find him curled up on the couch, vomiting uncontrollably. He had to be intubated and kept in an induced coma until his ammonia levels were brought under control.
So when a doctor told Jesse that a clinical trial for a potential OTCD treatment was in the works, he was very interested. Researchers at the University of Pennsylvania in Philadelphia were developing a fix for the OTC gene, which produces an enzyme that prevents ammonia buildup. Patients would be injected with working copies of the gene that had been attached to an adenovirus, a type of cold virus. The virus, altered to be harmless, would infect the patients’ liver cells and integrate the added gene into their chromosomal DNA.
