Guest post by Paul Jaffe, MAADDSG@aol.com; coordinator, Manhattan Adult Attention Deficit Disorder Support Group; New York, NY, USA. [7/17/08]

Recently, gene-therapy researchers — who have had their ups and downs — scored a point: the restoration of some vision to patients with retinal degeneration [1,2].

To effect this, they used a generally harmless adeno-associated virus (AAV). The goal was to deliver, to the retina, a functioning copy of a defective gene thought to trigger the illness. This viral “vector” was injected through a surgical procedure deemed reasonably safe.

Within gene therapy, AAV vectoring – which may soon turn a corner [3] — is now standard. This includes a well-publicized effort [4,5,6] — and a less-publicized effort [7] — to treat Parkinson’s Disease.

Unlike the above, which might be termed corrective gene therapy, the PD applications are closer to compensatory gene therapy. Here, the aim is to alter the brain so as to mimic a treatment several steps removed from an underlying pathology.

In each PD clinical trial, a gene has been inserted to encode a specific enzyme. These are:

• glutamic acid decarboxylase (GAD), which catalyzes the synthesis of the neurotransmitter gamma-aminobutyric acid (GABA); and
• human aromatic l-amino acid decarboxylase (AADC or hAADC), which does the same for dopamine (DA).

The vectors are known, respectively, as the AAV-GAD and the AAV-AADC.

The PD research might — or might not — succeed. (One vector is in US Phase II testing; the other, in Phase I.) The question here is: might either be used elsewhere? … Continue Reading »