Increased APOE ε4 expression is associated with the difference in Alzheimer's disease risk from diverse ancestral backgrounds

• Published in: Alzheimer's & dementia Vol. 17; no. 7; pp. 1179 - 1188
• Main Authors: Griswold, Anthony J., Celis, Katrina, Bussies, Parker L., Rajabli, Farid, Whitehead, Patrice L., Hamilton‐Nelson, Kara L., Beecham, Gary W., Dykxhoorn, Derek M., Nuytemans, Karen, Wang, Liyong, Gardner, Olivia K., Dorfsman, Daniel A., Bigio, Eileen H., Mesulam, Marek Marsel, Weintraub, Sandra, Geula, Changiz, Gearing, Marla, McGrath‐Martinez, Elisa, Dalgard, Clifton L., Scott, William K., Haines, Jonathan L., Pericak‐Vance, Margaret A., Young, Juan I., Vance, Jeffery M.
• Format: Journal Article
• Language: English
• Published: United States 01.07.2021
• Subjects: Aged; Aged, 80 and over; Alleles; Alzheimer Disease - ethnology; Alzheimer Disease - genetics; Alzheimer's disease; APOE; Apolipoprotein E4 - genetics; Black People - genetics; Female; Heterozygote; Humans; local ancestry; Male; Sequence Analysis, RNA; single‐nucleus RNA‐seq; White People - genetics; APOE; single-nucleus RNA-seq; local ancestry; Alzheimer's disease
• ISSN: 1552-5260; 1552-5279; 1552-5279
• DOI: 10.1002/alz.12287

Introduction Apolipoprotein E (APOE) ε4 confers less risk for Alzheimer's disease (AD) in carriers with African local genomic ancestry (ALA) than APOE ε4 carriers with European local ancestry (ELA). Cell type specific transcriptional variation between the two local ancestries (LAs) could contribute to this disease risk differences. Methods Single‐nucleus RNA sequencing was performed on frozen frontal cortex of homozygous APOE ε4/ε4 AD patients: seven with ELA, four with ALA. Results A total of 60,908 nuclei were sequenced. Within the LA region (chr19:44‐46Mb), APOE was the gene most differentially expressed, with ELA carriers having significantly more expression (overall P < 1.8E–317) in 24 of 32 cell clusters. The transcriptome of one astrocyte cluster, with high APOE ε4 expression and specific to ELA, is suggestive of A1 reactive astrocytes. Discussion AD patients with ELA expressed significantly greater levels of APOE than ALA APOE ε4 carriers. These differences in APOE expression could contribute to the reduced risk for AD seen in African APOE ε4 carriers.