Identification of SCA2 mutation in cases of spinocerebellar ataxia with no family history in mid-eastern Sicily

Abstract

Differential diagnosis between autosomal dominant cerebellar ataxia type I (ADCA I) and idiopathic cerebellar ataxia type P (IDCA-P) is very difficult given only clinical and neuroradiological data. The only certain distinctive characteristic is the presence or absence of family history. We observed 7 patients with late-onset cerebellar ataxia associated with other non-cerebellar signs and without a family history of the disease in which clinical signs were comparable to symptoms found in SCA2. The neuroradiological study showed olivopontocerebellar atrophy in all patients and the presence of hyperintensity of the transverse pontine fibers in 6 patients (85. 6%); molecular analysis showed SCA2 mutations in 2 patients. We also report the case of a patient who was initially considered as IDCA-P but who was later correctly identified as SCA2 with an atypical family history (false IDCA-P), after a genetic mutation was found and following an interview with the mother. Our data suggest that spinocerebellar ataxia syndrome should be defined as idiopathic not only after having excluded the possible symptomatic causes but also in the absence of family history, after having excluded the presence of genetic mutation. We believe that family history, in late-onset spinocerebellar ataxia, cannot be considered as the differential criterion among hereditary (ADCA-I) and non-hereditary (IDCA-P) forms; molecular analysis is required for a correct diagnosis.