ABSENCE OF LINKAGE DISEQUILIBRIUM AT AMYLOID PRECURSOR PROTEIN GENE LOCUS IN JAPANESE FAMILIAL ALZHEIMERS-DISEASE WITH 717VAL-]ILE MUTATION

To date, eleven independent FAD pedigrees with the 717Val-->Ile mutati on have been identified. Interestingly, five pedigrees were of Japanes e origin and four were of British origin. The apparent ethnic predicti on of this mutation raises the possibility that there is a founder eff ect in these two island nations. We did not observe any significant li nkage disequilibrium in any locus of APP and GT12 loci in the five Jap anese FAD pedigrees with the 717Val-->Ile mutation. A founder effect w ould probably not be present in Japanese FAD pedgrees with the 717Val- ->Ile mutation.