Hi there,
Just a little something for the two of you, Vic and Mike. And yes it is very good, Vic to see you doing so much better.

I'm starting to see more interest in the growing evidence of genetic disposition towards developing RSD. I have scattered links which at some point this week I'll gather into a proper post for you to take a look at.

What got me started was my interest in erythromelalgia, so similar to RSD that I couldn't see the difference. But they've isolated a specific gene for it, called SCN9A

SCN9A-Related Inherited Erythromelalgia
http://www.genetests.org/profiles/etha

SCN9A-related IEM is characterized by recurrent attacks of intense pain, redness, warmth, and swelling involving the feet, and less frequently, the hands [Drenth & Michiels 1994]. Warmth is an essential part of the syndrome. During the attacks, the extremities appear red or purple and may be swollen. Commonly, the attacks occur in the evening or at night and so may not be observed by a physician. The individual may seek medical advice for painful extremities, but neglect to mention the characteristic warmth or redness (especially if limited to the soles of the feet). The symptoms are usually bilateral and symmetric. Within a family, the manifestations of the disorder may vary considerably.

However, not all erythro sufferers have this gene.

Then, interestingly, there are other complications. They found a family of 6 kids in Pakistan with a genetic mutation of the SCN9A gene. They can't feel any pain at all.

"The mutation that takes away pain"
http://www.bioedonline.org/news/news.cfm?art=3002
The researchers compared DNA samples from the six children and found that they all share a mutation in a gene called SCN9A, which is strongly expressed in nerve cells. They report their results in Nature.
The SCN9A gene encodes a 'sodium channel': one of the structures that allows electrical charge to flow into nerve cells, triggering a signal, the researchers explain. Without this particular type of sodium channel, the brain does not receive any signal that the body has encountered a pain-causing stimulus.

You can see why I'm interested; then I saw something quite recently about the "growing evidence" for gene involvement in RSD. Can't find it this minute, but will post the missing info soon.

Anyway, something for you both to think about!
all the best