A yeast artificial chromosome contig from human chromosome 14q24 spanning the Alzheimer's disease locus AD3.

Familial Alzheimer's disease has been previously linked to three genetic loci on chromosomes 21, 19 and 14. The AD3 locus on chromosome 14 has not been cloned and the molecular defect in chromosome 14-linked AD3 families has yet to be identified. Genetic linkage analysis has placed the AD3 locus in band 14q24 between the dinucleotide markers D14S61 and D14S289, a genetic distance of approximately 6.4 cM. We have constructed a yeast artificial chromosome (YAC) contig that covers the entire minimal region, encompassing all genetic markers that are non-recombinant for the disease in AD3-linked families. This contig, constructed by using a combination of YAC end sequence walking and sequence-tagged site (STS) mapping, consists of 63 YACs from three different libraries. The AD3 contig contains 12 polymorphic dinucleotide repeat markers from D14S61 to D14S251, as well as an additional 43 non-polymorphic STSs. This contiguous physical map of the region will allow the physical distances between the markers to be determined, as well as providing a framework for the identification of candidate genes.