Subject number (n) 147 Genotype Age (years) Male (n) Current smoker (n) BMI (kg/m2) SBP (mmHg) DBP (mmHg) T-chol (mmol/L) HDL-C (mmol/L) LHDLC (n) TG (mmol/L) HbA1c (%) A/A + A/G 66 ± 12 67 (46%) 23 (16%) 22.2 ± 2.0 139 ± 20 77 ± 10 4.85 ± 0.87 1.44 ± 0.38 22 (15%) Non-obese G/G 45 66 ± 13 21 (47%) 8 (18%) 22.3 ± 1.9 135 ± 19 74 ± 10 4.94 ± 1.13 1.43 ± 0.38 6 (13%) Kotani et al J Clin Med Res • 2011;3(6):319-324 Table 1. The Clinical Characteristics of Subjects Based on the Genotypes of the Uncoupling Protein-1 Gene A-3826G Polymorphism in the Non-obese and Obese Groups - 0.98 0.90 0.73 0.64 0.26 0.08 0.69 0.94 0.79 0.24 0.97 P value A/A + A/G 75 63 ± 14 30 (40%) 9 (12%) 27.1 ± 1.9 139 ± 21 78 ± 13 4.86 ± 0.85 1.39 ± 0.36 9 (13%) Obese G/G 27 62 ± 15 9 (33%) 3 (11%) 27.4 ± 2.3 138 ± 17 80 ± 13 4.72 ± 0.97 1.20 ± 0.30 10 (37%) P value - 0.72 0.55 0.90 0.48 0.92 0.52 0.48 0.01* < 0.01* 0.86 0.85 0.98 (0.75-1.23) 0.98 (0.76-1.52) 5.6 ± 1.3 5.6 ± 1.3 1.05 (0.84-1.51) 1.15 (0.86-1.39) 5.6 ± 0.7 5.5 ± 0.6 BMI: body mass index; SBP: systolic blood pressure; DBP: diastolic blood pressure; T-chol: total cholesterol;, HDL-C: high-density lipoprotein cholesterol; LHDLC: low high-density lipoprotein cholesterolemia; TG: triglycerides; HbA1c: hemoglobin A1c. The data are expressed as the means ± standard deviation, medians (interquartile range) or subject number (%). Differences in data between the genotype-based groups were examined by the unpaired t-test or χ2-test within each group of non-obese and obese subjects. The TG values were log-transformed because of their skewed distribution in the analysis. Signiﬁcant level: *: P < 0.05. 14] as well as a possibly protective association of the G/G genotype with low HDL-cholesterolemia [15]. The UCP-1 expression is regulated by the condition of the individual, including the extent of obesity, and carrying the G allele is related to a reduced UCP-1 expression in obese subjects [9]. Therefore, the inconsistencies reported between studies on the association between the A-3826G polymorphism and HDL-C levels [8-15] may be, at least in part, explained by the difference in the studied populations, such as differences in the composition of obese and non-obese subjects. In fact, we noted that all of the studies showing that carrying the G allele or G/G genotype was signiﬁcantly associated with lower HDL-C levels were in obese populations {i.e., 42-47 kg/m2 [9], 33 kg/m2 [11], and 34 kg/m2 [13] for the mean body mass index (BMI)} except one study (mean BMI 45 kg/m2) [8], while studies showing no association between the A-3826G polymorphism and HDL-C [10, 12, 14] and carrying the G/G genotype as a protective factor for low HDL-cholesterolemia [15] were for relatively non-obese populations {i.e., mean BMI 25.5 kg/m2 (in Caucasians) [10], 22 kg/m2 [12], 22 kg/m2 [14], and 22-23 kg/m2 [15]}. Based on this background information, the present study aimed to compare the association between the UCP-1 gene A-3826G polymorphism and low HDL-cholesterolemia in a general Japanese population by analyzing subject-groups separated according to their obesity status. Methods This cross-sectional association study included a total of 294 community-dwelling Japanese subjects [127 males and 167 females, mean age 65 ± 13 (SD) years], recruited from community-based health check-ups conducted in the Mima area of Japan. The study was approved by the institutional ethics committee and each subject gave informed consent. The subjects who were basically asymptomatic and not tak- ing any medication were eligible. Excluded were subjects who suffered from any acute inﬂammatory disease, or had a clinical history of cardiovascular, thyroid, malignant, severe hepatic or renal diseases. Smoking habits were determined as a current or non- smoker through a self-reported questionnaire. In addition to the BMI, calculated as the body weight (kg) divided by the square of the height (m), the systolic blood pressure (SBP) and diastolic blood pressure (DBP) were measured in the seated subject’s right arm using a mercury sphygmomanom- eter. Blood was sampled after an overnight fast. The serum 320 Articles © The authors | Journal compilation © J Clin Med Res and Elmer Press™ | www.jocmr.org