Identification of a SGCD x Discrimination interaction effect on systolic blood pressure in African American adults in the Jackson Heart Study.

BACKGROUND: In the United States, hypertension disproportionately afflicts over half of African American adults, many of whom also experience racial discrimination. Understanding gene x discrimination effects may help explain racial disparities in hypertension.

METHODS: We tested for main effects and interactive effects of five candidate single nucleotide polymorphisms (SNPs: rs2116737, rs11190458, rs2445762, rs2597955, rs2416545) and experiences of discrimination on blood pressure (BP) in African Americans not taking antihypertensive medications in the Jackson Heart Study from Mississippi (n=2933). Multiple linear regression models assumed an additive genetic model and adjusted for ancestry, age, sex, body mass index, education, and relatedness. We additionally tested recessive and dominant genetic models.

RESULTS: Discrimination was significantly associated with higher diastolic BP (p=0.003). In contrast, there were no main effects of any SNP on BP. When analyzing SNPs and discrimination together, SGCD (Sarcoglycan Delta; rs2116737) demonstrated a gene x environment interaction. Specifically, a SGCD x Discrimination interaction was associated with systolic BP (β=1.95, p=0.00028) in a recessive model. Participants carrying a T allele, regardless of discrimination experiences, and participants with a GG genotype and high experiences of discrimination had higher systolic BP than participants with a GG genotype and low experiences of discrimination. This finding suggests the SGCD GG genotype may have a protective effect on systolic BP, but only in a setting of low discrimination.

CONCLUSIONS: The inclusion of culturally relevant stressors, like discrimination, may be important to understand the gene-environment interplay likely underlying complex diseases with racial health inequities.