|Summary||possible 2x increased risk of Alzheimer's disease for some people but maybe not others; see discussion|
Carriers of a minor allele for both rs1049296 (P589S) in the transferrin gene (TF) and rs1800562 (C282Y) in HFE may have a somewhat increased risk for Alzheimer's disease based on at least one publication, however, another publication finds this to only be true for ApoE4 carriers. Even if this finding is independent of ApoE4 status, it may not be applicable to non-Northern European populations.
The most recent study (2012) found that Northern European bi-carriers who were also ApoE4 carriers (see gs293) were at increased risk for AD (synergy factor 1.75, CI:1.1–2.8, p = 0.02).[PMID 20817350]
The previous study (2010) found that bi-carriers were overall at increased risk of AD, regardless of ApoE4 status, by a factor of 2.4 after adjusting for age and presence of the ApoE4 allele (p=0.002).[PMID 20029940]
The original 2004 study ([PMID 15060098]) found a higher synergy factor than the subsequent studies cited above.