EARLY-ONSET ALZHEIMERS-DISEASE IN A SOUTH-AMERICAN PEDIGREE FROM ARGENTINA

We report the clinical, SPET, immunohistochemical and DNA features of an early-onset familial Alzheimer's disease (FAD) in an Argentine pedi gree of South American indian ethnic background. Pedigree spans 5 gene rations comprising more than 110 biological relatives. Clinical data s upported the diagnosis of early onset FAD (mean age at onset 38.9 year s) in 10 family members, including 3 with pathological confirmation (m ean age at death 48.5). The pattern of transmission suggested autosoma l dominant inheritance. Prominent features were mood changes, early la nguage impairment, myoclonus, seizures and cerebellar signs. SPET disp layed bilateral frontal, temporo-parietal and cerebellar hypoperfusion in early stages and in an asymptomatic member at risk, suggesting tha t SPET may have predictive value in this family. Immunohistochemistry showed beta amyloid deposits within neuritic plaques and vessel walls and no anti-PrP immunoreactivity. DNA analysis showed no abnormalities in the beta amyloid precursor protein gene. The identification of add itional genetic defects in well characterized independent FAD pedigree s will contribute to the understanding of the pathogenesis of Alzheime r's disease.