Identification of FXTAS presenting with SCA 12 like phenotype in India.

BACKGROUND

Fragile X-associated Tremor/Ataxia syndrome (FXTAS) is a clinically heterogeneous disorder characterized predominantly by tremor, followed by late onset gait ataxia, autonomic dysfunction and/or cognitive impairment. We aimed to screen FMR1-CGG repeats in our cohort of progressive late-onset cerebellar ataxia/tremor cohort to characterize the occurrence of FXTAS in India.

METHODS

We have screened FMR1-CGG repeats in 109 patients and 173 healthy control subjects. Our cohort comprised: a)group of patients with predominant cerebellar ataxia and/or tremor. b.)suspected cases of MSA and c.)patients who presented SCA12-like neurological manifestations (late onset predominant tremor and/or ataxia). All the cases were ruled out for known triplet-repeat-expansion (TRE) SCA mutations.

RESULTS

We have found three FMR1-premutation carriers among the cases. Two of them (with CGG-96 and CGG-102) were under evaluation for their SCA12-like manifestations and another (CGG-78) had progressive gait ataxia. Overall the frequency of FXTAS in our cohort was found to be 3.3% among cases of late onset cerebellar-ataxia/tremor; however, incidences were higher among cases with SCA12-like syndrome (9%, 2/23).

CONCLUSION

Finding FXTAS in patients with SCA12-like manifestation suggests that TRE in the 5'UTR of the gene is the common cue connecting two disorders with common phenotype of tremor/ataxia. This knowledge might shed light upon their sharing of molecular neuropathology.