Monozygotic twins concordant for probable Alzheimer disease and increased platelet membrane fluidity

Abstract

This report describes monozygotic twins who were concordant for probable Alzheimer disease, as defined by currently-accepted clinical criteria. Monozygosity was established by blood typing. Their ages of symptomatic onset were 57 and 66 yr, and the times from onset to institutionalization were 8 and 2 yr, respectively. These results suggest that age at onset and rate of progression are clinical features that can be affected by random processes or exposure to environmental factors. The platelet membrane fluidity of both twins was abnormally increased, and the respective values were identical within experimental limits. This result is consistent with published data suggesting that increased platelet membrane fluidity is associated with a clinically distinct subtype of Alzheimer disease and that this platelet membrane characteristic may be genetically determined.

Regional Cerebral Glucose Metabolism in Monozygotic Twins Discordant for Alzheimer’s Disease

“…On the other hand, when monozygotic twins are discordant for AD, differences in environmental exposure are likely to have determined the development of the disease [19]. In longitudinal studies, the onset of AD between monozygotic co-twins who eventually become concordant has varied by several years [14,20,21], indicating the contribution of environmental factors to the manifestation age of disease.…”

Monozygotic twins concordant for late‐onset probable alzheimer disease with suspected alzheimer disease in four sibs

“…We are aware of detailed published reports of proven or suspected Alzheimer disease (AD) in 34 pairs of monozygotic (MZ) twins, with established concordance for the disease in 15 of these pairs and apparent discordance in the remaining 19 [Davidson and Robertson, 1955;Hunter et al, 1972;Sharman et al, 1979;Cook et al, 1981, Kilpatrick et al, 1983Doi et al, 1984; Embry and Lippman, 1985;Renvoize et al, 1986;Luxenberg et al, 1987;Nee et al, 1987;Fitch et al, 1988;Resnick et al, 1988;Zubenko and Ferrell, 1988;Creasey et al, 1989; Kumar et al, 19911. Methodological problems concerned with accurate diagnosis of AD during life and its age-ofonset, with length of follow-up in seemingly unaffected co-twins and, to a lesser extent, with proof of zygosity can make interpretation of some of the available data difficult.…”