First gene therapy for Tay-Sachs disease successfully given to two children

Two babies have received the first-ever gene therapy for Tay-Sachs disease after over 14 years of development.

Tay-Sachs is a severe neurological disease caused by a deficiency in an enzyme called HexA. This enzyme breaks down a fatlike substance that normally exists in very small, harmless amounts in the brain. Without HexA, however, this fatlike substance can accumulate to toxic levels that damage and kill neurons.

One of the symptoms of this disease was first described in 1883 by British ophthalmologist Warren Tay, who saw a cherry-red spot on the back of the eye of affected infants. In 1887, American neurologist Bernard Sachs described the profound neurological symptoms of Tay-Sachs in a seminal paper:

“… Nothing abnormal was noticed until the age of two to three months, when the parents observed that the child was much more listless than children of that age. … The child would ordinarily lay upon its back, and was never able to change its position … it never attempted any voluntary movement … the child grew steadily weaker, it ceased to take its food...