Association of mitochondrial genome variants with Alzheimer's disease in a Chinese population.

BackgroundResearch on the mitochondrial genome variants of Alzheimer's disease (AD) in Chinese populations is lacking.ObjectiveThe study aimed to identify mitochondrial DNA (mtDNA) variants associated with AD risk and explore the relationship between mtDNA variants and plasma biomarkers in AD patients.MethodsWhole genome sequencing was performed in 1509 AD patients and 2010 controls from the Chinese population. mtDNA variants were called according to GATK's best practice mitochondrial pipeline. We evaluated the association of AD risk with mtDNA variants and mitochondrial haplogroup. Common variant (MAF≥0.01) based association analysis and gene-based tests of rare variants (MAF<0.01) were carried out with PLINK 1.9 and SKAT-O, respectively. Spearman correlation analysis was performed to assess the association between the burden of mtDNA variants and plasma biomarker levels.ResultsThe frequency of mitochondrial haplogroup G in AD group was nominally higher than control group (p = 0.019, OR = 1.48). Rare variants of MT-CYB gene were significantly enriched in controls compared to AD patients (p = 2.81 × 10-4, OR = 0.886). Besides, the control group exhibited considerably lower mRNA expression of MT-CYB in brain regions compared to AD patients in GEO database. Furthermore, the number of mtDNA indel variants per individual correlated positively with plasma Aβ42 levels.ConclusionsMitochondrial haplogroup G may serve as a risk factor for AD, while rare variants of MT-CYB gene acted as protective factor against AD in mainland China. Moreover, mtDNA variants were related to AD plasma biomarker levels. Our findings highlighted the role of mitochondrial genome variants in the pathogenesis of AD.