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
TTallele

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.