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Genetic Ancestry Markers and Difference in A1c Between African American and White in the Diabetes Prevention Program.

Citation
Hivert, M. -F., et al. “Genetic Ancestry Markers And Difference In A1C Between African American And White In The Diabetes Prevention Program.”. The Journal Of Clinical Endocrinology And Metabolism, pp. 328-336.
Center University of Michigan University of Washington
Multicenter
Multicenter
Author Marie-France Hivert, Costas A Christophi, Kathleen A Jablonski, Sharon L Edelstein, Steven E Kahn, Sherita Hill Golden, Samuel Dagogo-Jack, Kieren J Mather, José A Luchsinger, Enrique Caballero, Elizabeth Barrett-Connor, William C Knowler, Jose C Florez, William H Herman
Abstract

Purpose: HbA1c levels are higher in blacks than non-Hispanic whites (NHWs). We investigated whether genetics could explain this difference in Diabetes Prevention Program (DPP) participants.

Methods: We tested (i) genetic variants causing hemoglobinopathies, (ii) a genetic risk score (GRS) based on 60 variants associated with HbA1c from genome-wide association meta-analysis, and (iii) principal component (PC) factors that capture continental ancestry derived from genetic markers distributed across the genome.

Results: Of 2658 eligible DPP participants, 537 (20%) self-identified as black and 1476 (56%) as NHW. Despite comparable fasting and 2-hour glucose levels, blacks had higher HbA1c (mean ± SD = 6.2 ± 0.6%) compared with NHWs (5.8 ± 0.4%; P < 0.001). In blacks, the genetic variant causing sickle cell trait was associated with higher HbA1c [β (SE) = +0.44 (0.08)%; P = 2.1 × 10-4]. The GRS was associated with HbA1c in both blacks and NHWs. Self-identified blacks were distributed along the first PC axis, as expected in mixed ancestry populations. The first PC explained 60% of the 0.4% difference in HbA1c between blacks and NHWs, whereas the sickle cell variant explained 16% and GRS explained 14%.

Conclusions: A large proportion of HbA1c difference between blacks and NHWs was associated with the first PC factor, suggesting that unidentified genetic markers influence HbA1c in blacks in addition to nongenetic factors.

Year of Publication
2019
Journal
The Journal of clinical endocrinology and metabolism
Volume
104
Issue
2
Number of Pages
328-336
Date Published
12/2019
ISSN Number
1945-7197
DOI
10.1210/jc.2018-01416
Alternate Journal
J. Clin. Endocrinol. Metab.
PMID
30358859
PMCID
PMC6300069
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