Familial Aggregation of Metabolic Syndrome With Different Socio-Behavioral Characteristics: The Fourth Phase of Tehran Lipid and Glucose Study

BACKGROUND: Since genetic and most environmental factors shape the context of families, some studies have been initiated to investigate the role of familial relationships in metabolic syndrome (MetS). OBJECTIVES: To estimate the familial aggregation of MetS and its components by identifying both case and control probands among Tehranian adults with different socio-behavioral and reproductive characteristics. PATIENTS AND METHODS: This case-controlled/family-based study was conducted on 1,777 families (635 case probands) who participated in the Tehran Lipid and Glucose Study (TLGS). Socio-demographic and reproductive information including levels of education, marital status, occupation status, age at menarche, number of abortions, number of children, and lifestyle habits such as smoking, physical activity and regular diet were obtained from the TLGS data bank. Metabolic syndrome was defined according to the joint interim statement (JIS) criteria. To estimate the regression co-efficient for familial aggregation and environmental factors, the generalized estimation equation method was used. RESULTS: The risk of having MetS among family members for case versus control probands was 2.19 (95% CI: 1.68 - 2.84), which, after adjusting for potential confounders including age, sex, educational level, marital status, occupation, age at menarche and energy, soft drink and starchy vegetable intake, increased to 2.31 (95% CI: 1.81 - 2.94; P < 0.05). Compared to control probands, the risk of having MetS components increased significantly from OR = 1.28 for both high waist circumference (WC) and blood pressure (BP) to OR = 1.72 for high triglycerides in cases. Familial aggregation inherited from the father was significantly observed in all MetS components, from adjusted OR = 1.63 for hyperglycemia to adjusted OR = 2.69 for high WC, except for low HDL, after controlling for potential confounders. CONCLUSIONS: Considering spouses and siblings, there was a higher risk for MetS components among families whose fathers and offspring had MetS components, implying the pivotal role of genetic inheritance in the incidence of the syndrome and its components.