Imagine you have an adorable baby who’s oddly slow to start sitting up. You get the child tested and to your horror, the verdict is a genetic death sentence: Tay-Sachs Disease. Exceedingly rare, but inexorably fatal. You now know that your baby likely won’t live to kindergarten age, and instead of growing up will slide down into blindness, seizures, paralysis. No cure. No hope.
That is how Tay-Sachs Disease has tended to unfold, since it was first described in the late 19th century. But now, for the first time, scientists say, there is a chance — though it is far from certain — that in the foreseeable future, that merciless course could be altered.
If all goes as planned, in the second half of next year researchers from the University of Massachusetts Medical School, Massachusetts General Hospital and elsewhere will launch a clinical trial of a new gene therapy treatment in up to 12 children with Tay-Sachs Disease.
The treatment involves infusing, deep into the brain, engineered viruses that can effectively turn cells in the brain into “micro-factories” of the enzyme that is so lethally absent in people with the disease. Cats with a feline version of Tay-Sachs normally die by about age four months. The gene therapy treatment has kept them going strong beyond 18 months.
“This is the first time there’s a real prospect for a possible treatment for Tay-Sachs and similar genetic diseases that affect the brain,” said Susan Kahn, executive director of the National Tay-Sachs & Allied Diseases Association (NTSAD), a driving force behind the research along with other family foundations. “Parents who had affected children as far back as the 1950s are saying, ‘Wow, I never thought I would see this day.'”
Now for the inevitable cautions, from UMass researcher Miguel Sena-Esteves:
“Usually, in my first breath, I tell people about the great results we’re observing in the cats,” he said. “In the second breath, I tell them there’s absolutely no guarantee that because we’re getting these results in animals, we’ll see the same in a human. We know from experiments in many, many fields that what works in another species doesn’t necessarily work in a human. If it did, we would have cured cancer by now.”
Also, gene therapy, in particular, has a past marked by some major disappointments. Touted as a potential cure for just about anything in the 1990s, it all but crashed after an 18-year-old patient died of a massive immune reaction in 1999 and it turned out that the viruses used as “vectors” to carry the genes sometimes induced leukemia.
Lately, however, gene therapy has begun to rack up successes, said Dr. Terence Flotte, dean of the UMass School of Medicine and himself a gene therapy researcher. It helped restore some vision in blind people with a rare genetic disease of the retina, he noted, and seems to show particular promise for diseases of the brain and central nervous system.