Possible ethnic differences in plasma homocysteine levels associated with coronary artery disease between South Asian and East Asian immigrants

Background. Hyperhomocysteinemia has been identified as a risk factor for coronary artery disease (CAD). South Asians appear to have a high incidence of CAD, while East Asians have a very low incidence. Hypothesis: The present study was undertaken because the relative association of plasma homocysteine levels (PH) with CAD in South Asians (SA = Indian, Pakistani, Sri Lankan) and East Asians (EA = Chinese, Japanese) is not known. Methods: Fasting PH were drawn on all patients with CAD of SA (age 62.4 +/- 1.1 years, 72 men, 14 women) and EA (age 61.8 +/- 3.0 years, 13 men, 4 women) descent. These were compared with PH available from Caucasian (CA) patients (age 61.1 +/- 1.1 years, 89 men, 17 women) with CAD. Results: The PH in SA, EA, and CA patients were 11.0 +/- 0.5, 7.6 +/- 0.5, and 10.8 +/- 0.6 mu mol/l, respectively (p < 0.001 between EA and SA/CA). Percentages of SA, EA, and CA with elevated PH (> 12.0 mu mol/L) were 33.7, 5.9, and 28.2%, respectively. There were no significant differences in the lipid subfractions between the SA and EA group. History of smoking was significantly higher in the EA (52.9 vs. 26.2%), while hypertension and diabetes mellitus had similar prevalences. Conclusion: Significant differences in PH of SA versus EA patients with CAD exist. The relative contribution of homocysteine in the development of CAD appears to be less in EA immigrants. In contrast, the association between CAD and PH in SA immigrants appears to be similar to that of Caucasians.