LINKAGE DISEQUILIBRIUM BETWEEN FD1-D9S202 HAPLOTYPES AND THE FRIEDREICHS ATAXIA LOCUS IN A CENTRAL-SOUTHERN ITALIAN POPULATION

We used two recently described genetic markers in the region of the Fr iedreich's ataxia locus to study 33 affected pedigrees from central-so uthern regions of Italy. These markers are predicted, by physical mapp ing, to be localised more closely to the Friedreich's ataxia locus tha n other previously described markers. No recombination was found betwe en these markers and the disease locus. Strong linkage disequilibrium is present between the compound haplotype and the disease locus. Since this population was also previously studied by using three other more distal genetic markers, a total of five markers has been used to iden tify the extended haplotype. Homozygosity in consanguineous pedigrees was also studied. Extended haplotype analysis and homozygosity studies suggest the presence of few common disease causing mutations in our p opulation.