Type 2 deiodinase p.Thr92Ala polymorphism does not affect the severity of obesity and weight loss after bariatric surgery

Abstract

A single nucleotide polymorphism in the Type 2 deiodinase (DIO2) gene (p.Thr92Ala) was found to be associated with hypertension, type 2 diabetes mellitus (T2DM), insulin resistance, and body mass index (BMI). We retrospectively evaluated 182 patients to assess whether the DIO2 p.Thr92Ala was associated with severe obesity and response to bariatric surgery. Genomic DNA was extracted from peripheral blood leukocytes before surgery. Glycemic control parameters, cardiometabolic risk biomarkers (waist circumference, lipid assessment and blood pressure) and hormonal parameters were assessed at baseline and after surgery. Based on genotype evaluation, 78/182 (42.9%) patients were homozygous wild-type (Thr/Thr), 83/182 (45.6%) heterozygous (Thr/Ala), and 21/182 (11.5%) rare homozygous (Ala/Ala). Age at the time of the first evaluation in our Unit was significantly lower in patients with DIO2 p.Thr92Ala. No significant association was observed between DIO2 p.Thr92Ala and BMI, excess weight, waist circumference, Homa Index. The prevalence of comorbidities was not associated with allele distribution except for hypertension that was more frequent in wild-type patients (p = 0.03). After bariatric surgery, excess weight loss (EWL) % and remission from comorbidities occurred without differences according to genotypes. DIO2 p.Thr92Ala does not affect the severity of obesity and its complications, but it seems to determine an earlier onset of morbid obesity. The presence of polymorphism seems not to impact on the response to bariatric surgery, both in terms of weight loss and remission of comorbidities.

Genetic variants associated with weight loss and metabolic outcomes after bariatric surgery: A systematic review

“…Follow‐up ranged from 6 months to 7 years. Weight loss was expressed as change in BMI in 11 studies, 25–34 percentage excess BMI loss (EBMIL) in one study, 35 percentage TWL in nine studies, 36–44 and excess weight loss (EWL) in 29 studies 45–73 . Patients underwent various types of bariatric procedures including RYGB, SG, and LAGB.…”

“…For numerous genes, only one or more SNPs were examined, and no significant association was found between the genetic variant and weight loss after bariatric surgery 33,36,40,42,46,47,54,58,63,67,68,73 …”

“…25,29,33,38,41,44,49,56,59,73 3.10.2 | Genes with no statistically significant association with weight loss For numerous genes, only one or more SNPs were examined, and no significant association was found between the genetic variant and weight loss after bariatric surgery. 33,36,40,42,46,47,54,58,63,67,68,73…”

Current Understanding of Human Polymorphism in Selenoprotein Genes: A Review of Its Significance as a Risk Biomarker

“…The TT genotype was associated with a better outcome one year after acute ischemic stroke than one minor G allele in Lithuania patients [110]. Some studies could not find an association between the polymorphisms and certain diseases: Thr92Ala polymorphism and the severity of obesity after bariatric surgery in Italy [112], Thr92Ala polymorphism and cognitive impairment in older adults in Brazil [113], rs12885300 polymorphism and the body weight variation after Graves' disease treatment in Brazil [109], and rs12095080, rs11206244, rs2235544 polymorphisms in DIO 1 and rs225014 and rs225015 in DIO2 with acute ischemic stroke outcome [110].…”