Does the mitochondrial genome play a role in the etiology of Alzheimer's disease?
We report here the analyses of complete mtDNA coding region sequences from more than 270 Alzheimer's disease (AD) patients and normal controls to determine if inherited mtDNA mutations contribute to the etiology of AD. The AD patients and normal individuals were carefully screened and drawn from two populations of European descent in an effort to avoid spurious effects due to local population anomalies. Overall, there were no significant haplogroup associations in the combined AD and normal control sequence sets. Reduced median network analysis revealed that the AD mtDNA sequences contained a higher number of substitutions in tRNA genes, and that there was an elevated frequency of replacement substitutions in the complex I genes of the control sequences. Analysis of the replacement substitutions indicated that those arising in the AD mtDNAs were no more deleterious, on average, than those in the control mtDNAs. The only evidence for the synergistic action of mutations was the presence of both a rare non-conservative replacement substitution and a tRNA mutation in 2 AD mtDNAs, from a total of 145, whereas such a combination of mutations was not observed in the control sequences. Overall, the results reported here indicate that pathogenic inherited mtDNA mutations do not constitute a major etiological factor in sporadic AD. At most, a small proportion of AD patients carry a pathogenic mtDNA mutation and a small proportion of cognitively normal aged individuals carry a mtDNA mutation that reduces the risk of AD.
Elson
Joanna L
JL
Mitochondrial Research Group, School of Neurology, Neurobiology, and Psychiatry, The University of Newcastle upon Tyne, and Institute for the Health of the Elderly, Newcastle General Hospital, Newcastle upon Tyne, United Kingdom.
Herrnstadt
Corinna
C
Preston
Gwen
G
Thal
Leon
L
Morris
Christopher M
CM
Edwardson
J A
JA
Beal
M Flint
MF
Turnbull
Douglass M
DM
Howell
Neil
N
D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000235:genetics*; D016022:Case-Control Studies; D004252:DNA Mutational Analysis; D004272:DNA, Mitochondrial / Q000502:physiology*; D006239:Haplotypes; D006801:Humans; D009154:Mutation; D011110:Polymorphism, Genetic
D004272:DNA, Mitochondrial