Common and ethnic-specific genetic determinants of hemoglobin concentration between Taiwanese Han Chinese and European Whites: findings from comparative two-stage genome-wide association studies

The Chinese cardiorespiratory and circulatory system at work in women and men: a case-control study

Background

The physiology of prominent prognostic factors in the cardiorespiratory system remains unchartered in the world's largest ethnic group: Hans Chinese (HC). This study assessed and contrasted the fundamental variables in HC and European-American (EA) individuals.

Methods

Healthy HC and EA adults (n = 140, 43% ♀) closely matched by age, sex and physical activity were included. Body composition (DXA) and haematological variables (haemoglobin mass, blood volume (BV)) were measured at rest. Pulmonary O2 uptake (VO2) measurements along with cycle ergometry designed for accurate transthoracic echocardiography were implemented to assess cardiorespiratory structure/function up to peak effort.

Findings

HC presented with higher body fat and lower lean body mass (LBM) percentage than EA irrespective of sex (P ≤ 0.014). BV did not differ whereas blood haemoglobin concentration was lower in HC compared with EA, particularly in females (P = 0.009). Myocardial diastolic and overall function at rest was enhanced in HC versus EA (P < 0.001). During exercise, heart volumes and output per unit of body size did not differ between ethnicities, whereas larger heart volumes per unit of LBM were found in HC versus EA in females (P ≤ 0.003). At high exercise intensities, VO2 (-16%) and the arteriovenous O2 difference (-28%) were markedly reduced in HC compared with EA in females (P ≤ 0.024). In males, no physiological difference between HC and EA was observed during exercise.

Interpretation

Notwithstanding lower LBM, HC are characterised by similar BV and cardiac capacity but reduced peak VO2 than EA in females, partly explained by low ethnic-specific blood O2 carrying capacity.

Funding

Early Career Scheme (106210224, to D.M.) and Seed Fund (104006024, to D.M.).

Positive or U-Shaped Association of Elevated Hemoglobin Concentration Levels with Metabolic Syndrome and Metabolic Components: Findings from Taiwan Biobank and UK Biobank

Iron overnutrition has been implicated with a higher risk of developing metabolic and cardiovascular diseases, including metabolic syndrome (MetS), whereas iron deficiency anemia exacerbates many underlying chronic conditions. Hemoglobin (Hb) concentration in the blood, which reflects a major functional iron (i.e., heme iron) in the body, may serve as a surrogate of the nutritional status of iron. We conducted sex-specific observational association studies in which we carefully titrated the association between Hb deciles and MetS and its components among the Taiwanese Han Chinese (HC) from the Taiwan Biobank and Europeans of White ancestry from the UK Biobank, representing two large ethnicities. Our data show that at higher-than-normal levels of Hb, increasing deciles of Hb concentration were significantly associated with MetS across all sex subgroups in both ethnicities, with the highest deciles resulting in up to three times greater risk than the reference group [Taiwanese HC: OR = 3.17 (95% CI, 2.75-3.67) for Hb ≥ 16.5 g/dL in men, OR = 3.11 (2.78-3.47) for Hb ≥ 14.5 g/dL in women; European Whites: OR = 1.89 (1.80-1.98) for Hb ≥ 16.24 g/dL in men, OR = 2.35 (2.24-2.47) for Hb ≥ 14.68 g/dL in women]. The association between stronger risks and increasing Hb deciles was similarly observed with all metabolic components except diabetes. Here we found that both the highest Hb decile groups and contrarily the lowest ones, with respect to the reference, were associated with higher odds of diabetes in both ethnic groups [e.g., Taiwanese HC men: OR = 1.64 (1.33-2.02) for Hb ≥ 16.5 g/dL, OR = 1.71 (1.39-2.10) for Hb ≤ 13.5 g/dL; European Whites women: OR = 1.39 (1.26-1.45) for Hb ≥ 14.68 g/dL, OR = 1.81 (1.63-2.01) for Hb ≤ 12.39 g/dL]. These findings confirm that elevated Hb concentrations, a potential indicator of iron overnutrition, may play a role in the pathophysiology of MetS and metabolic components.