The effect of TOMM40 on spatial navigation in amnestic mild cognitive impairment.

Laczó J, Andel R, Vyhnalek M, Matoska V, Kaplan V, Nedelska Z, Lerch O, Gazova I, Moffat SD, Hort J. Neurobiology of Aging. 2015 Jun;36(6):2024–33. doi: 10.1016/j.neurobiolaging.2015.03.004. Epub 2015 Mar 16. IF: 5.013

doc.MUDr. Jan Laczó, Ph.D.

doc. MUDr. Jan Laczó, Ph.D., Department of Neurology

Abstract

The very long (VL) poly-T variant at rs10524523 ("523") of the TOMM40 gene may hasten the onset of late-onset Alzheimer's disease (LOAD) and induce more profound cognitive impairment compared with the short (S) poly-T variant. We examined the influence of TOMM40 ‘523’ polymorphism on spatial navigation and its brain structural correlates. Participants were apolipoprotein E (APOE) ε3/ε3 homozygotes with amnestic mild cognitive impairment (aMCI). The homozygotes were chosen because APOE ε3/ε3 variant is considered ‘neutral’ with respect to LOAD risk. The participants were stratified according to poly-T length polymorphisms at ‘523’ into homozygous for S (S/S; n = 16), homozygous for VL (VL/VL; n = 15) TOMM40 poly-T variant, and heterozygous (S/VL; n = 28) groups. Neuropsychological examination and testing in real-space human analog of the Morris Water Maze were administered. Both self-centered (egocentric) and world-centered (allocentric) spatial navigation was assessed. Brain magnetic resonance imaging scans were analyzed using FreeSurfer software. The S/S group, although similar to S/VL and VL/VL groups in demographic and neuropsychological profiles, performed better on allocentric navigation (p ≤ 0.004) and allocentric delayed recall (p ≤ 0.014), but not on egocentric navigation. Both S/VL and VL/VL groups had thinner right entorhinal cortex (p ≤ 0.043) than the S/S group, whereas only the VL/VL group had thinner left entorhinal cortex (p = 0.043) and left posterior cingulate cortex (p = 0.024) than the S/S group. In conclusion, TOMM40 ‘523’ VL variants are related to impairment in allocentric spatial navigation and reduced cortical thickness of specific brain regions among aMCI individuals with (LOAD neutral) APOE ε3/ε3 genotype. This may reflect a specific role of TOMM40 ‘523’ in the pathogenesis of LOAD.

http://www.ncbi.nlm.nih.gov/pubmed/25862420

Created: 7. 6. 2016 / Modified: 12. 4. 2019 / Mgr. Ing. Tereza Kůstková