--you and pabb and Mrs D already have most of the comments/bases covered that I would have touched on, Kiwiboy.

I do think that this paper and the mouse model is very much in the tradition of twenty-first century research into neurological research that attempts to regrow hard-to-regenerate neural tissue by genetic manipulation--there's been a lot of work within this paradigm investigating possible spinal cord regeneration for those with traumatic injury (especially given the military injuries from Iraq and Afghanistan)--but that application to humans is a long way off. There have unfortunately been a lot of dead ends regarding genetic manipulation and nerve growth factors when the research that worked well for small mammals was then attempted with primates, even before getting to human trials . . .

Science Daily is OK--is just tends to aggregate and report on studies that have been accepted to more specific scientific journals. One can go to PubMed or Google Scholar and often get the original study and related studies.

And yes, neuronopathy of the dorsal root ganglia is not very well understood, though it tends to have the non-length dependent characteristics you've described. Since it's very hard to image dorsal root ganglia, evidence of the process is sort of indirect. Toxic and autoimmune mechanisms would seem to be primary etiologies. And while some have reported some improvement with immune-modulating therapies--steroids or IVIg--improvement is often patchy at best, because we haven't yet found good ways to get nerve cell bodies to repair, and these are what are damaged in neuronopathies; the immune modulating therapies seem merely to slow down or arrest the damage process, allowing other cells to take over some functin from damaged ones. Unlike axons, which can regenerate if damaged when the cell body is intact, if cell bodies die, they are not normally replaceable. That is why the genetic manipulation studies are so exciting, if we can re-program cells to re-grow or become the specialized sensory cells of the dorsal root ganglia.