Evaluation of the frequency of ADIPOQ c.45 T > G and ADIPOQ c.276 G > T polymorphisms in adiponectin coding gene in girls with anorexia nervosa

Introduction: Anorexia nervosa (AN) is a serious chronic psychosomatic disorder, the essence of which are attempts by the sufferer to obtain a slim silhouette by deliberate weight loss (restrictive diet, strenuous physical exercise, provoking vomiting). The aetiology of this disorder is multifactorial. Genetic factors that influence the predisposition to AN have been sought. A broad meta-analysis points to a strong genetic correlation between AN and insulin resistance. Adiponectin (ADIPO) increases insulin sensitivity. In our pilot study we demonstrated that the TT genotype in locus ADIPOQ c.276 G>T of the ADIPO gene and a higher concentration of ADIPO in blood serum occurred significantly more frequently in 68 girls suffering from AN than in 38 healthy girls. The objective of this study was to evaluate the frequency of the occurrence of ADIPOQ c.45 T>G and ADIPOQ c.276 G>T in the ADIPO gene in a larger cohort of girls with AN and healthy girls, as well as an analysis of correlations between variants of the aforementioned polymorphisms and the levels of ADIPO in blood serum. Material and methods: The study covered 472 girls (age: 11-19 years): 308 with the restrictive form of AN (AN) and 164 healthy girls (C). The level of ADIPO in blood serum was determined by means of the ELISA method on a Bio-Vendor, LLC (Asheville, North Carolina, USA). The DNA isolation was carried out by means of Genomic Mini AX BLOOD (SPIN). The PCR reaction was carried out in a ThermoCycle T100 thermocycler. 80-150 ng of the studied DNA and relevant F and R starters were added to the reaction mixture. The reaction products were subjected to digestion by restriction enzymes and separated on agarose gels (RFLP). Results: The distribution of genotypes in the polymorphic site ADP c.45 of the ADIPO gene and ADP c.276 was similar in both groups. In both groups the T allele was most frequent in locus ADIPOQ c.45 and the G allele in locus ADIPOQ c.276. In all the study subjects collectively (AN and C) a statistically significant negative correlation between the levels of ADIPO in blood serum on one hand and body weight (r = -0.46; p < 0.0001) and BMI (r = -0.67; p < 0.0001) on the other was demonstrated. Exclusively in the AN group a significant correlation between the level of ADIPO in blood and the distribution of TG, TT, and GG alleles in loci ADIPOQ c.45 and ADIPOQ c.276 was demonstrated (p = 0.0052 and p < 0.0001, respectively). Conclusions: The genotype in loci ADIPOQ c.45 and ADIPOQ c.276 of the ADIPO gene seems to have no effect on the predisposition to AN. Girls suffering from AN with the TT genotype in loci ADIPOQ c.45 and ADIPOQ c. 276 may demonstrate higher insulin sensitivity because they have significantly higher levels of ADIPO than girls suffering from AN with other genotypes. This may be suggestive of their better adaptation to the state of malnutrition, and it has a potential effect on treatment results.