Linked to 1. VDR:   Absence VDR Low fat mass, resistance to fat-induced obesity and reduced plasma lipid levels Atrophy of the adipose tissue surrounding the prostate and mammary glands VDR Polymorphism Total fat mass in young Chinese men TaqI TT allele Increase prevalence of obesity in type 2 DM FokIEffect on insulin sensitivity and serum HDL-cholesterol ff genotype Increase in waist-to-hip ratio Adverse metabolic profile bb genotype Increased prevalence of obesity in type 2 DM BsmI Human body weight and BMI   No predisposition to obesity and insulin resistance BB allele Higher BMI and waist circumference relative to bb allele Unfavorable lipid profile short poly A- repeat (ss) Higher body weight and fat mass 2. Polycystic Ovary Syndrome: Central obesity and insulin resistance (PCOS) + Low 25OHD concentrations Correlated with insulin resistance, metabolic risk factors, and obesity + Serum PTH levels Higher in PCOS patients than ovulatory women without hyperandrogenemia + Vitamin D treatment Improved glucose metabolism and menstrual frequency + ApaI genotype “Aa” of VDR Appeared to be a marker of decreased PCOS susceptibility. +ApaI genotype“aa” of VDR Associated with an increased risk for PCOS + VDR ApaI variants Associated with testosterone levels in PCOS women. 3. Cytochrome P450: • CYP27B1 Converts 25OHD3 to 1,25OHD3 Express in adipose tissue and function in adipocytes Lacking CYP27B1 Lean phenotype with hypoleptinemiaandhyperphagia 4. Chromosome 20: Clone for 1,25OHD3 24-hydroxylase Variant at 20.13 Risk for vitamin D deficiency Obesity PTPN1 Essential hypertension, obesity (Japaneseand Chinese) Mutation at 20q13.3 Pseudohypoparathyroidismand obesity Variant at 20q13.2 Influence plasma levels of adiponectinand C-protein 5. Vitamin D-binding protein (DBP): DBP gene Contains conserved nucleotide sequences that respond to adipocyticand mitotic signals   For vitamin D cellular endocytosis and metabolism DBP gene variant Obesity-related trait in Caucasian nuclear families VDR, vitamin D receptor; DM, diabetes mellitus; HDL, high density lipoprotein; 25OHD3, 25-hydroxyvitamin D3; 1,25OHD3, 1,25-dihydroxyvitamin D3; PTPN1, protein tyrosine phosphatase 1β

Table 1: The relationship between allelic variations in vitamin D and obesity.