Three papers in the December 22 (2000) issue of Science present evidence for a gene or genes on chromosome 10 that may be involved in genetic susceptibility to late-onset Alzheimer's disease [Bertram, L. et al (2000) Science 290, 2302-2303 (Abstract); Ertekin-Taner, N. et al (2000) Science 290, 2303-2304 (Abstract); Myers, A. et al (2000) Science 290, 2304-2305 (Abstract)]. Myers et al studied a large set of affected sib pairs, looking across the genome for alleles shared by these sibs significantly more often than would be expected by chance. Ertekin-Taner et al looked for genes linked to elevated levels of the blood protein Ab42, which are thought to be associated with Alzheimer's susceptibility. Both groups pinpointed a specific region of chromosome 10, which can now be examined in further detail. The third group carried out a linkage study in families, reporting linkage of late-onset Alzheimer's in these families to a different region of chromosome 10 from that identified in the other two studies.
Comment: It is too soon to say what the eventual fate of these reported linkages will be. The fact that two of the studies, using completely different approaches, have homed in on the same region of the same chromosome is encouraging, but further independent verification is still needed. Eventually, of course, a specific candidate gene must be identified in the region and susceptibility must be convincingly linked to a specific allele or alleles.