OBJECTIVE: To investigate the genetics of depression among individuals of East Asian and European descent living in different geographic locations, and with different outcome definitions for depression.
DESIGN, SETTING, AND PARTICIPANTS: Genome-wide association analyses followed by meta-analysis, which included data from 9 cohort and case-control data sets comprising individuals with depression and control individuals of East Asian descent. This study was conducted between January 2019 and May 2021.
EXPOSURES: Associations of genetic variants with depression risk were assessed using generalized linear mixed models and logistic regression. The results were combined across studies using fixed-effects meta-analyses. These were subsequently also meta-analyzed with the largest published GWAS for depression among individuals of European descent. Additional meta-analyses were carried out separately by outcome definition (clinical depression vs symptom-based depression) and region (East Asian countries vs Western countries) for East Asian ancestry cohorts.
MAIN OUTCOMES AND MEASURES: Depression status was defined based on health records and self-report questionnaires.
RESULTS: There were a total of 194 548 study participants (approximate mean age, 51.3 years; 62.8% women). Participants included 15 771 individuals with depression and 178 777 control individuals of East Asian descent. Five novel associations were identified, including 1 in the meta-analysis for broad depression among those of East Asian descent: rs4656484 (β = -0.018, SE = 0.003, P = 4.43x10-8) at 1q24.1. Another locus at 7p21.2 was associated in a meta-analysis restricted to geographically East Asian studies (β = 0.028, SE = 0.005, P = 6.48x10-9 for rs10240457). The lead variants of these 2 novel loci were not associated with depression risk in European ancestry cohorts (β = -0.003, SE = 0.005, P = .53 for rs4656484 and β = -0.005, SE = 0.004, P = .28 for rs10240457). Only 11% of depression loci previously identified in individuals of European descent reached nominal significance levels in the individuals of East Asian descent. The transancestry genetic correlation between cohorts of East Asian and European descent for clinical depression was r = 0.413 (SE = 0.159). Clinical depression risk was negatively genetically correlated with body mass index in individuals of East Asian descent (r = -0.212, SE = 0.084), contrary to findings for individuals of European descent.
CONCLUSIONS AND RELEVANCE: These results support caution against generalizing findings about depression risk factors across populations and highlight the need to increase the ancestral and geographic diversity of samples with consistent phenotyping.
METHODS: Data from death records, 1998-2002, and from 2001 Census data were extracted for seven migrant groups [New Zealand; United Kingdom (UK)/Ireland; Germany; Greece; Italy; China/Singapore/Malaysia/Vietnam (East Asia); and India/Sri Lanka (South Asia)] aged 45-64 years. Poisson regression models were fitted to estimate the duration of residence effect (categorized in 5-year bands and also as having arrived 2-16, 17-31 and 32 years ago or more), adjusted for sex, 5-year age group and year of death, then additionally for occupational class and marital status (SES) on relative risks (RR) of CVD mortality.
RESULTS: Compared with the Australia-born population, CVD mortality was generally lower in each migrant group. Decreasing mortality with increasing duration of residence was observed for migrants from New Zealand (RR 0.95, 95% Confidence Interval 0.92-0.98, P<0.01, per 5-year increase), Greece (0.90, 0.86-0.94, P<0.01), Italy (0.94, 0.91-0.97, P<0.01) and South Asia (0.95, 0.91-0.99, P<0.01), mainly in older age groups. Trends remained after SES adjustment and also when broader categories of duration of residence were used. CVD mortality among migrants from the UK/Ireland appeared to converge towards those of the Australian-born.
CONCLUSIONS: These results show divergence in CVD mortality compared with the Australian rate for New Zealanders, Greeks, Italians and South Asians. Sustained cardio-protective behavioural practices in the Australian setting is a potential explanation.