Drug hypersensitivity is a common symptom for patients with fibromyalgia and chronic fatigue syndrome, both poorly understood diseases that are diagnosed by a process of exclusion.

In this study the author found...

"Many drug hypersensitivity reactions are HLA-linked, meaning that they will occur much more often or even exclusively in individuals who have certain variants of the HLA gene,"

HLA genes are also heavily involved with MHC molecules, immunity and autoimmunity.

If fibromyalgia/CFS drug hypersensitivity was a result of these HLA mutations could it signal an immunolgical/ autoimmune root cause for the disease, perhaps centered around other HLA mutations?

http://www.liai.org/pages/news-releases_may_29_2012