URBANIZATION ELICITS A MORE ATHEROGENIC LIPOPROTEIN PROFILE IN CARRIERS OF THE APOLIPOPROTEIN A-IV-2 ALLELE THAN IN A-IV-1 HOMOZYGOTES

Coronary heart disease (CHD) is increasing in developing countries, pa rticularly in urban areas. The impact of urbanization and apolipoprote in (ape) A-IV genetic polymorphism on plasma lipoproteins was studied in 222 men and 236 women from rural and urban Costa Rica. The apoA-IV allele frequencies were 0.937 for apoA-IV-1 and 0.062 for apoA-IV-2. S ignificant interactions between the apoA-IV polymorphism and area of r esidence (rural versus urban) were detected for HDL cholesterol (P=.00 3). apoA-I (P=.05), LDL particle size (P=.01), and LDL/HDL cholesterol ratio (P=.005). Urban compared with rural carriers of the apoA-IV-2 a llele had significantly lower plasma HDL cholesterol (0.95 versus 1.17 mmol/L) and apoA-I (980 versus 1140 mg/L), a significantly higher LDL /HDL cholesterol ratio (3.35 versus 2.39), and significantly smaller L DL particles (258 versus 263 Angstrom). In contrast, no significant ru ral-urban differences for these parameters were found in apoA-IV-1 hom ozygotes. Regardless of their apoA-IV phenotype, urban residents consu med more saturated fat (P=.02) and smoked more cigarettes per day (P=. 03) than rural residents. A significant interaction between saturated fat intake and apoA-IV phenotype was found for HDL cholesterol (P<.000 3) and LDL/HDL cholesterol ratio (P<.003). Increased saturated fat int ake (13.6% versus 8.6% of calories) was significantly associated with 6%, higher HDL cholesterol and no change (0.7%) in LDL/HDL cholesterol ratio in apoA-IV-1 homozygotes and with 19% lower HDL cholesterol and 37% higher LDL/HDL cholesterol ratio among carriers of the apoA-IV-2 allele. Smokers (greater than or equal to 1 cigarette per day) had sig nificantly lower HDL cholesterol (P<.005) and apoA-I (P<.01) concentra tions than nonsmokers (<1 cigarette per day), particularly among carri ers of the apoA-IV-2 allele (-19% and -13%) compared with apoA-IV-1 (- 4% for both). After taking these lifestyle characteristics into accoun t, the areas of residence by phenotype interactions for plasma lipopro tein concentrations were no longer statistically significant. Lifestyl es associated with an urban environment. such as increased smoking and saturated fat intake, elicit a more adverse plasma lipoprotein profil e among Costa Rican carriers of the apoA-IV-2 allele than in apoA-IV-1 homozygotes. Therefore, under the conditions studied, persons with th e apoA-IV-2 allele may be more susceptible to CHD.