Fluoroquinolone toxicity creates a syndrome. Fluoroquinolone Toxicity (FQAD) is a novel syndrome that mimics many different disease processes, such as MS, Fibromyalgia, Chronic Fatigue Syndrome, etc… Yet, even though it may mimic these other pathologies, it also sets itself apart in many areas. Many sufferers experience wider ranging and more intense symptoms than many who experience the organic disease processes.
Due to lack of research and guidance form the FDA many doctors are woefully ignorant to Fluoroquinolone toxicity and the syndrome that it causes. There needs to be intensive academic research that defines the causal mechanisms and damages that manifest after an adverse event is experienced.
The Fluoroquinolones can and do damage and exert pressure in several different ways. First, they have the ability to cause direct DNA damage. Second, they have the ability to exert tremendous epigenetic pressure thereby ‘switching' on or off’ genes and creating a pathogenic process. Third, they set the state for extreme states of oxidative stress that damages cell structures and influences gene selection. Fourth, they can directly damage delicate cellular structures such as lysosomes, cell membranes, and external and internal cellular proteins responsible for cellular communication and more. These are just a few of the more prevalent ways that Fluoroquinolones do damage to the human body.
I have seen genetic results from literally dozens of floxed folks, and at this time it would appear that there is no clear genetic predispositions to floxing, including MTHFR.  Genetic tests from severely floxed individuals has shown no mutually shared genetic markers.   There is some indications that certain CYP polymorphisms may lead to more extensive metabolization in some individuals and this clue needs further research.