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The ADIPOQ gene gives instructions for making the adiponectin hormone. This gene is expressed exclusively in differentiated adipocytes, and its resulting hormone circulates in the plasma and reaches the muscle and liver cells. Adiponectin has 244 amino acids and shares structural homology with collagen VIII, X, and complement C1q. It has three forms: a low-molecular weight (LMW) of 67 kDa, a hexamer of 120 kDa, and a high molecular weight (HMW) of >300. Adiponectin reduces the fat and improves insulin sensitivity by initiating fat burning and glucose utilization processes. Adiponectin has direct anti-diabetic, anti-atherogenic, and anti-inflammatory activities. Some studies have also shown that variants in the ADIPOQ gene play a role in age-associated diseases.
The ADIPOQ gene is located on chromosome 3q27. It consists of two coding exons and spans about 16 kb of genomic DNA. The ADIPOQ gene has many variants. The most common variants are the T/G polymorphism of SNP +45 in exon 2 and the G/T polymorphism of SNP +276 in intron 2. Adiponectin protein levels have been associated with serum insulin levels, insulin resistance, type 2 diabetes, and cardiovascular diseases.
Khabour et al. (2010) investigated the possible contribution of the rs266729 (-11377G/C), rs2241766 (+45T/G), and rs1501299 (+276 G/T) SNPs of adiponectin gene (ADIPQO) to human longevity phenotype in Jordanian population. Polymorphisms were genotyped in 110 randomly selected elderly subjects (>85 years old) with mean age of 90.2 years, and 120 young control subjects (range from 20 to 50 years) with mean age of 32.0 years. No significant differences were detected in the genotype and allele frequencies of examined gene variants between the two groups (p > 0.05). However, when gender was considered, the genotype and allele frequency of rs1501299 (+276 G/T) was significantly associated with longevity in men (p < 0.02), but not in women (p > 0.05).
In 2013, Alkhateeb et al. examined the contribution of the promoter variant rs266729 (-11377C>G) of the ADIPOQ gene as a risk factor for diabetic patients in 420 type 2 diabetic patients and 230 controls from Jordan. The results showed a significant genotypic (p=0.00001) and allelic (p=0.01) association with variant in the diabetic patients as compared to controls.
Rizk et al. (2013) performed Real-Time Polymerase Chain Reaction for two SNPs (T45G and G276T) of the AdipoQ gene to investigate the association between the polymorphisms and adiponectin levels with acute coronary syndrome (ACS) in Qatar. A total of 142 patients with ACS and 122 controls were included in the study. The results showed that the TT, TG, and GG genotype for T45G were significantly different among cases and controls, whereas there was no significant difference for the G2746T polymorphism. Only the +45G allele was significantly associated with 3-fold increased risk of ACS in the affected patients. Patients with ACS who carry GG alleles had significantly lower adiponectin levels compared to TT/TG carriers of T45G.
