The Hide and Seek Foundation is the central organization for Lysosomal Storage Disease, the category to which Bertrand's disease belongs. On their site, they discuss the experimental treatments.
Enzyme replacement therapy is expensive, can't prevent or delay mental retardation, and it only works for about four of the fifty disorders. Injected enzymes can't cross the blood-brain barrier.
A bone marrow transplant, if successful, would allow the enzymes to be produced, and to cross the blood-brain barrier, possibly halting further mental retardation. This would also require finding a compatible bone marrow donor as fast as possible. Using another baby's healthy cord blood for transplantation is another possible treatment.
Stem cell transplants are a promising treatment option, but not enough research has been done yet. Conceivably, healthy stem cells could be injected into his marrow. Then, he could grow his own marrow to produce the enzymes he needs, without the risk of rejection. Unfortunately, stem-cell research has been effectively banned until last week, when President Obama lifted the ban. The lifting is years too late for Bertrand.
The only hope for a cure is gene therapy, in which a specially constructed virus would effectively "infect" Bertrand and repair every cell in his body. In the long run, gene therapy will be the way to go, but at present, there just hasn't been enough research to make it safe. [All attempts to date involving gene therapy have killed the patient with the specially constructed virus.]
Sadly, none of these options can reverse the damage that's already been done, even if totally successful.
We'll be consulting with Bertrand's physicians, but it looks like bone marrow and/or cord-blood transplants are in his future. Of course, there are major risks associated with these options, and there's no guarantee they'll work. But, we have to try, and we have to try quickly.