FMR1 and fragile X-associated tremor/ataxia syndrome: Some authors have suggested that all clinical manifestations associated with the PM of the FMR1 gene constitute a spectrum of varying degrees of penetrance and severity of these clinical signs, in which the final diagnosis of FXTAS or FXPOI may represent extreme forms of cognitive and endocrine impairment that may be present in other PM carriers in a milder manner.