TOMM40 poly-T variants and cerebrospinal fluid amyloid beta levels in the elderly.

A variable poly-T polymorphism in the TOMM40 gene, which is in linkage disequilibrium with APOE, was recently implicated with increased risk and earlier onset age for late-onset Alzheimer's disease in APOE ε3 carriers. To elucidate potential neurobiological mechanisms underlying this association, we compared the effect of TOMM40 poly-T variants to the effect of APOE, an established LOAD-risk modulator, on cerebrospinal fluid (CSF) amyloid beta (Aβ) and tau levels, in cognitively intact elderly subjects. APOE ε4 carriers showed significant reductions in Aβ 1-42 levels compared to non-ε4 carriers, but no differences were detected across TOMM40 variants. Neither Aβ 1-40 nor tau levels were affected by APOE or TOMM40.