Inflammatory Gene Variants in the Tsimane, an Indigenous Bolivian Population with a High Infectious Load

Abstract

The Tsimane of lowland Bolivia are an indigenous forager-farmer population living under conditions resembling pre-industrial European populations, with high infectious morbidity, high infection and inflammation, and shortened life expectancy. Analysis of 917 persons ages 5 to 60⁺ showed that allele frequencies of 9 SNPs examined in the apolipoprotein E (apoE), C-reactive protein (CRP), and interleukin-6 (IL-6) genes differed from some European, African, and north Asian-derived populations. The apoE2 allele was absent, whereas four SNPs related to CRP and IL-6 were monomorphic: CRP (rs1800947, rs3093061, and rs3093062) and IL-6 (rs1800795). No significant differences in apoE, CRP, and IL-6 variants across age were found CRP levels were higher in carriers of two CRP proinflammatory SNPs, whereas they were lower in carriers of apoE4. Taken together, the evidence for (1) different allele frequencies between the Tsimane and other populations and (2) the correlations of CRP and apoE alleles with blood CRP may suggest that these variants are under selection in response to a high infection environment.

Acknowledgments

We gratefully acknowledge the Tsimane people for their participation in this study. We also thank the members of the Tsimane Health and Life History Project, especially Dr. Daniel Eid Rodriguez, Dr. Edhitt Cortez Linares, Dr. Karen Arce Ardaya, Jhon Aguilar and Ivan Maldonado. This work was supported by grants from the National Institute on Aging (R01AG024119-01, P30AG17265, R21AG031988, T32AG0037) (HK, MG, EMC); the National Heart, Lung, and Blood Institute (R01HL079353) (HA);, the National Center for Research Resources (M01-RR-00043, RR10600-01, CA62528-01, RR14514-01) (HA); the National Science Foundation (BCS-0136274 and BCS-0422690) (HK, MG); the Keck Foundation (CEF, EMC); the USC Oakley Fellowship Fund (SV); the Ellison Medical Foundation (CEF); and the Ziegler Fund (CEF, EMC).