Recruiting American Indian women for a genetic epidemiology study

The Experiences of American Indian Participants and Site Coordinators in a Gestational Diabetes Risk Reduction Trial

Gestational diabetes mellitus is the most common complication of pregnancy and contributes to increased risk for type 2 diabetes in both the mother and offspring. We developed and evaluated a gestational diabetes risk reduction and preconception counseling program, Stopping GDM (SGDM), for American Indian females. The purpose of this study is to examine the experiences of American Indian mother-daughter dyad participants and the site coordinators who facilitated the SGDM randomized controlled trial to inform program revisions. We engaged mother-daughter dyads (n = 22 dyads) and site coordinators (n = 6) in focus group interviews. Four themes emerged: (1) SGDM sparked valuable quality conversation for dyads; (2) gestational diabetes risk factors and risk reduction was new information for most dyads; (3) all trial sites experienced challenges to recruitment and engagement; and (4) study-improvement recommendations. These findings will be used to enhance SGDM to decrease adverse intergenerational health impacts of gestational diabetes in American Indian communities.

Genetic analysis of hsCRP in American Indians: The Strong Heart Family Study

Background

Increased serum levels of C-reactive protein (CRP), an important component of the innate immune response, are associated with increased risk of cardiovascular disease (CVD). Multiple single nucleotide polymorphisms (SNP) have been identified which are associated with CRP levels, and Mendelian randomization studies have shown a positive association between SNPs increasing CRP expression and risk of colon cancer (but thus far not CVD). The effects of individual genetic variants often interact with the genetic background of a population and hence we sought to resolve the genetic determinants of serum CRP in a number of American Indian populations.

Methods

The Strong Heart Family Study (SHFS) has serum CRP measurements from 2428 tribal members, recruited as large families from three regions of the United States. Microsatellite markers and MetaboChip defined SNP genotypes were incorporated into variance components, decomposition-based linkage and association analyses.

Results

CRP levels exhibited significant heritability (h² = 0.33 ± 0.05, p<1.3 X 10⁻²⁰). A locus on chromosome (chr) 6, near marker D6S281 (approximately at 169.6 Mb, GRCh38/hg38) showed suggestive linkage (LOD = 1.9) to CRP levels. No individual SNPs were found associated with CRP levels after Bonferroni adjustment for multiple testing (threshold <7.77 x 10⁻⁷), however, we found nominal associations, many of which replicate previous findings at the CRP, HNF1A and 7 other loci. In addition, we report association of 46 SNPs located at 7 novel loci on chromosomes 2, 5, 6(2 loci), 9, 10 and 17, with an average of 15.3 Kb between SNPs and all with p-values less than 7.2 X 10⁻⁴.

Conclusion

In agreement with evidence from other populations, these data show CRP serum levels are under considerable genetic influence; and include loci, such as near CRP and other genes, that replicate results from other ethnic groups. These findings also suggest possible novel loci on chr 6 and other chromosomes that warrant further investigation.