Why cant Babies with Tay-Sachs disease not be treated by injecting the missing enzyme into their blood?

Babies with Tay-Sachs disease lack a specific enzyme called hexosaminidase A, which is crucial for breaking down certain lipids in the brain. Injecting the missing enzyme into the bloodstream is ineffective because the enzyme cannot cross the blood-brain barrier, which protects the brain from potential toxins but also prevents therapeutic agents from reaching brain tissues. Consequently, the buildup of harmful substances continues, leading to the progressive neurological damage characteristic of the disease. As of now, there are no effective treatments to reverse its effects.