Early onset of neurological symptoms in fragile X premutation carriers exposed to neurotoxins.

We present four cases of fragile X premutation carriers with early neurological symptoms, including symptoms consistent with multiple sclerosis (MS) and fragile X-associated tremor/ataxia syndrome (FXTAS). Each patient had significant exposure to one or more environmental neurotoxicants that have documented neurotoxicity (i.e. hexachlorocyclopentadiene or C56, Agent Orange, and 2,4- or 2,6-toluene diisocyanate and dichlormate). We hypothesize that premutation carriers are a vulnerable group to neurotoxins because elevated mRNA in the premutation can lead to early cell death and brain disease, leading to neuropsychiatric and neurological symptoms consistent with FXTAS.