re: Asperger's Syndrome could be the CAUSE of Social Anxiety
Asperger's has an extremely high comorbidity rate with other disorders such as anxiety.
There isn't much research on the links between this condition and SAD but there is emerging evidence for things such as higher rates of social anxiety disorder being found in first degree relatives of autistic probands. But there was no link found within individuals between SAD and the broad autistic phenotype. (See Piven J, Palmer P; Psychiatric disorder and broad autism phenotype. AmJ Psychiatry 1999, 156:557-563). This would seem counter intuitive seeing as there's a high comorbidity with anxiety (Bellini, 2004; Kim, Szatmari, Bryson, Streiner, & Wilson, 2000; Tonge, Brereton, Gray, & Einfeld, 1999), and this combined with the repercussions socially of the condition. Clearly much research is lacking.
But seeing as there's an overlap in various criteria between certain conditions, sometimes striking, it's easy for people with SAD to jump to conclusions about what else they might have. So caution is needed.
Also, did you notice this part of the Wiki article below?
Peter Szatmari suggests that Asperger's was promoted as a diagnosis to spark more research into the syndrome - "It was introduced into the official classification systems in 1994 and has grown in popularity as a diagnosis, even though its validity has not been clearly established. It is interesting to note that it was introduced not so much as an indication of its status as a 'true' disorder, but more to stimulate research ... its validity is very much in question."