DIO2 Polymorphism Research Articles

Association of DIO2 and MCT10 Polymorphisms With Persistent Symptoms in LT4-Treated Patients in the UK Biobank.

Some evidence suggests gene-treatment interactions might cause persistent symptoms in individuals receiving levothyroxine (LT4) treatment. We investigated, as previously hypothesized, if single-nucleotide variations (SNVs; formerly single-nucleotide polymorphisms) in rs225014 (Thr92Ala), rs225015, or rs12885300 (ORFa-Gly3Asp) in the deiodinase 2 gene (DIO2), or rs17606253 in the monocarboxylate transporter 10 gene (MCT10) were associated with outcomes indicative of local tissue hypothyroidism in LT4-treated patients and controls. We included 18 761 LT4-treated patients and 360 534 controls in a population-based cross-sectional study in the UK Biobank. LT4 treatment was defined as a diagnosis of hypothyroidism and self-reported use of LT4 without use of 3,5,3'-triiodothyronine. Outcomes were psychological well-being, cognitive function, and cardiovascular risk factors. Associations were evaluated by linear, logistic, or ordinal logistic multiple regression. Adjustments included sex, age, sex-age interaction, and genetic principal components 1 to 10. Compared to controls, LT4 treatment was adversely associated with almost all outcomes, most noteworthy: Increased frequency of tiredness (P < .001), decreased well-being factor score (P < .001), increased reaction-time (P < .001), and increased body mass index (P < .001). Except for a significant association between the minor rs225015 A allele and financial dissatisfaction, there was no association of rs225014, rs225015, rs12885300, or rs17606253 with any outcomes in LT4-treated patients. For all outcomes, carrying the risk allele at these 4 SNVs did not amplify symptoms associated with LT4 treatment compared to controls. rs225014, rs225015, rs12885300, and rs17606253 could not explain changed psychological well-being, cognitive function, or cardiovascular risk factors in LT4-treated patients. Our findings do not support a gene-treatment interaction between these SNVs and LT4 treatment.

Interaction between DIO2 polymorphisms and LT4 treatment on psychological well-being outcomes and cardiovascular risk factors: a population-based cross-sectional study in uk biobank

Interaction between DIO2 polymorphisms and LT4 treatment on psychological well-being outcomes and cardiovascular risk factors: a population-based cross-sectional study in uk biobank

Association between DIO2 Thr92Ala polymorphism and hypertension in patients with hypothyroidism: Korean Genome and Epidemiology Study.

Recent evidence has identified the significance of type 2 iodothyronine deiodinase (DIO2) in various diseases. However, the role of DIO2 polymorphism in metabolic parameters in patients with hypothyroidism is not fully understood. We assessed the polymorphism of the DIO2 gene and various clinical parameters in 118 patients who were diagnosed with hypothyroidism from the Ansan-Anseong cohort of the Korean Genome and Epidemiology Study. Furthermore, we systematically analyzed Genotype-Tissue Expression (GTEx) data. A total of 118 participants with hypothyroidism were recruited; 32 (27.1%) were homozygous for the Thr allele, 86 (73.9%) were homozygous for the Ala allele or heterozygous. Patients with hypothyroidism with DIO2 polymorphism without hypertension at baseline had higher incidence of hypertension compared to patients without DIO2 polymorphism. Analysis of the GTEx database revealed that elevation of DIO2 expression is associated with enhancement of genes involved in blood vessel regulation and angiogenesis. Commonly inherited variation in the DIO2 gene is associated with high blood pressure and prevalence of hypertension in patients with hypothyroidism. Our results suggest that genetic variation in the hypothalamic-pituitary-thyroid pathway in influencing susceptibility to hypertension.

Type 2 Deiodinase Thr92Ala Polymorphism Is Not Associated with Cognitive Impairment in Older Adults: A Cross-Sectional Study.

Background: Type 2 Deiodinase (DIO2) converts thyroxine (T4) into the active hormone triiodothyronine (T3). Thr92Ala DIO2 polymorphism has been associated with reduced conversion of T4 into T3 and central nervous system hypothyroidism. However, how Thr92Ala DIO2 polymorphism affects cognitive function is still unclear. Objective: To assess the association between Thr92Ala DIO2 polymorphism and cognitive performance in older adults. Design: Cross-sectional study. Setting: University-based tertiary hospital in Brazil. Patients: > 65-year-old with no limiting clinical disease. Interventions: All participants answered a standard questionnaire before undergoing thyroid function laboratory evaluation and genotyping of the Thr92Ala DIO2 polymorphism. Main Outcomes: Cognitive impairment measured by the Word List Memory task from the Consortium to Establish a Registry for Alzheimer’s Disease Neuropsychological Battery (CERAD-NB) and the Brief Cognitive Screening Battery (BCSB). Results: A hundred individuals were included. Clinical and laboratory characteristics were similar among DIO2 genotypes (all p > 0.05). No differences were found in the Word List Memory, recall, or recognition tests of the CERAD-NB assuming a recessive model for the Ala/Ala vs. Thr/Ala-Thr/Thr genotypes. Results of Clock Drawing Test, Animal Fluency Test, Mini-Mental State Exam, and Figure Memory Test of the BCSB were similar between groups. Conclusions: These findings suggest that Thr92Ala DIO2 polymorphism is not associated with relevant cognitive impairment in older adults.

An Assessment of GPX1 (rs1050450), DIO2 (rs225014) and SEPP1 (rs7579) Gene Polymorphisms in Women with Endometrial Cancer.

Background: Numerous studies indicate a relationship between the presence of GPX1 (rs1050450), DIO2 (rs225014) and SEPP1 (rs7579) gene polymorphisms and the development of chronic or neoplastic diseases. However, there are no reports on the influence of these polymorphisms on the development of endometrial cancer. Methods: 543 women participated in the study. The study group consisted of 269 patients with diagnosed endometrial cancer. The control group consisted of 274 healthy women. Blood samples were drawn from all the participants. The PCR-RFLP method was used to determine polymorphisms in the DIO2 (rs225014) and GPX1 (rs1050450) genes. The analysis of polymorphisms in the SEPP1 (rs7579) gene was performed by means of TaqMan probes. Results: There was a 1.99-fold higher risk of developing endometrial cancer in CC homozygotes, DIO2 (rs225014) polymorphism (95% Cl 1.14–3.53, p = 0.017), compared to TT homozygotes. There was no correlation between the occurrence of GPX1 (rs1050450) and SEPP1 (rs7579) polymorphisms and endometrial cancer. Conclusion: Carriers of the DIO2 (rs225014) polymorphism may be predisposed to the development of endometrial cancer. Further research confirming this relationship is recommended.

Meta-analysis of Association Studies of Selenoprotein Gene Polymorphism and Kashin-Beck Disease: an Updated Systematic Review.

To evaluate the association between selenoprotein gene polymorphisms and Kashin-Beck disease (KBD) susceptibility through a systematic review and updated meta-analysis. PubMed, Google Scholar, Cochrane library, and Chinese National Knowledge Infrastructure (CNKI) were electronically searched using the terms "selenoprotein" and "Kashin-Beck disease" or "KBD" with a search time from the establishment of the database to January 2021. The Newcastle-Ottawa Scale (NOS) was used for methodological quality evaluation of the included studies. Stata 14.0 software was used to pooled odds ratio (OR) and 95% confidence interval. There were a total of eight included case-control studies covering 2025 KBD patients and 1962 controls. Meta-analysis results show that the pooled odds ratios (OR) and 95% confidence intervals (CI) for DIO2 (rs225014) were 0.69 (0.52, 0.91), 0.69 (0.50, 0.96), and 0.72 (0.52, 0.99) in the allele, heterozygote, and dominant models, respectively. The OR and 95%CI for SEPS1 (-105G>A) were 2.47 (1.85, 3.29), 9.36 (4.58, 19.12), 2.17 (1.53, 3.08), and 8.60 (4.25, 17.38) in the allele, homozygote, dominant, and recessive models, respectively. In addition, the OR and 95%CI for Sep15 (rs5859) were 2.05 (1.06, 3.96) in the allele model. These results illustrate that there was a significant association between DIO2 (rs225014), SEPS1 (-105G>A), Sep15 (rs5859), and KBD. For GPX1 (rs1050450, rs1800668, rs3811699), DIO2 (rs225014, rs1352815, rs1388382), TrxR2 (rs1139793, rs5746841), GPX4 (rs713041, rs4807542), and SEPP1 (rs7579, 25191g/a), there was no significant statistical difference between the KBD and control groups (P>0.05). We conclude that the DIO2 (rs225014), SEPS1 (-105G>A), and Sep15 (rs5859) gene polymorphism are associated with susceptibility to KBD.

The polymorphic inheritance of DIO2 rs225014 may predict body weight variation after Graves' disease treatment.

We aimed to investigate the role of DIO2 polymorphisms rs225014 and rs12885300 in Graves' disease patients, mainly for controlling body weight following treatment. We genotyped 280 GD patients by the time of diagnosis and 297 healthy control individuals using a TaqMan SNP Genotyping technique. We followed up 141 patients for 18.94 ± 6.59 months after treatment. There was no relationship between the investigated polymorphisms with susceptibility to GD and gain or loss of weight after GD treatment. However, the polymorphic inheritance (CC+CT genotype) of DIO2 rs225014 was associated with a lower body weight variation after GD treatment (4.26 ± 6.25 kg) when compared to wild type TT genotype (6.34 ± 7.26 kg; p = 0.0456 adjusted for the follow-up time). This data was confirmed by a multivariate analysis (p = 0.0138) along with a longer follow-up period (p = 0.0228), older age (p = 0.0306), treatment with radioiodine (p-value = 0.0080) and polymorphic inheritance of DIO2 rs12885300 (p = 0.0306). We suggest that DIO2 rs225014 genotyping may have an auxiliary role in predicting the post-treatment weight behavior of GD patients.

Mice harbouring the minor allele of the human DIO2 polymorphism (Thr92Ala) are protected against osteoarthritis

Mice harbouring the minor allele of the human DIO2 polymorphism (Thr92Ala) are protected against osteoarthritis

Type 2 deiodinase Thr92Ala polymorphism is associated with a reduction in bone mineral density: A community-based korean genome and epidemiology study.

Type 2 deiodinase (DIO2)-mediated thyroid hormone synthesis stimulates osteoblast activity and increases the expression of osteoblast differentiation markers, but there are no large cohort studies to identify the role of the DIO2 polymorphism in bone mineral density in humans. To investigate the hypothesis that individuals with the DIO2 gene polymorphism are susceptible to osteoporosis, we assessed the polymorphism of the DIO2 gene in 7,524 Koreans drawn from the large-scale Ansan-Anseong cohort of the Korean Genome and Epidemiology Study. All of the participants underwent genotyping of the DIO2 Thr92Ala polymorphism (rs225014). A total of 6,022 participants were recruited; 1991 (33.0%) were homozygous for the Thr allele, 2,967 (49.3%) were heterozygous (Thr/Ala), and 1064 (17.7%) were homozygous for the Ala allele. The effects of the DIO2 Thr92Ala polymorphism on axial speed of sound (SOS) and the T-score in the tibia and radius were assessed, with age, gender, oestrogen status, body mass index (BMI), serum calcium, 25-hydroxyvitamin D, and parathyroid hormone (PTH) included as covariables. Female subjects carrying the DIO2 Thr92Ala polymorphism had significantly lower SOS and T-scores than control participants. Cox regression analysis revealed a significant relationship between the DIO2 polymorphism and diagnosis of osteoporosis in female participants. DIO2 Thr92Ala polymorphism is associated with decreased SOS and T-scores in the tibia of female subjects independent of other clinical parameters, where this indicates a potential functional role of DIO2 in the maintenance of bone mineral density.

Association between DIO2 polymorphism and the risk of Kashin-Beck disease in the Tibetan population.

Kashin-Beck disease (KBD) is a local, multiple and deformable osteoarthropathy, mostly occurring in Tibet. Type 2 iodothyronine deiodinase (DIO2) is implicated in the activation of thyroid hormones to which the bones are very sensitive. Therefore, it is necessary to explore the association between KBD and DIO2 in the Tibetan population. We carried out a case-control study among 316 cases and 320 controls from a Tibetan population. Seven single nucleotide polymorphisms in DIO2 were selected and genotyped using the Agena MassARRAY platform (Agena Bioscience, San Diego, CA, USA). Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated by logistic regression analysis. HaploReg (https://pubs.broadinstitute.org/mammals/haploreg/haploreg.php) and GTEx (http://www.gtexportal.org) databases were applied for functional assessment of the polymorphisms. The "A/C" genotype of rs1352815 (OR=3.18, 95% CI=1.14-8.85, p=0.027) and the "A/G" genotype of rs1388382 (OR=3.80, 95% CI=1.30-11.11, p=0.015) were associated with the susceptibility of KBD under the co-dominant model. With gender stratification analysis, rs1388382 showed obvious evidence for correlation with an elevated risk of KBD in females under the co-dominant model (OR=3.32, 95% CI=1.06-10.41, p=0.039). The results obtained in the present study indicate that DIO2 polymorphisms rs1352815 and rs1388382 were correlated with KBD susceptibility among Tibetans, which also sheds new light on the role of DIO2 in the development of KBD.

A study of the role of DIO1 and DIO2 polymorphism in thyroid cancer and drug response to therapy in the Saudi population

BackgroundDeiodinases comprise a group of selenoproteins that regulate the bioavailability of active thyroid hormones (TH) in a time and tissue specific fashion. They increase the hormonal activity by metabolizing their inactive precursors to active forms or terminate their activity by deactivating active hormones. The role of the deiodinase (DIO) gene polymorphisms in thyroid cancer is not fully understood yet. This study evaluated the potential association of the DIO1 and DIO2 genes with differentiated thyroid cancer and differential thyroxine dose requirement in thyroidectomized patients in a Saudi cohort. MethodsWe selected four variants (one DIO1 and three DIO2) for the association studies using Taqman assays in 507 DTC patients undergoing treatment with thyroxin against 560 disease-free individual, all of Saudi Arab origin. ResultsNone of the studied variants was linked to differentiated thyroid cancer. The rs1388378_G > T was initially linked to thyroxine dose requirement (p = 0.035) when all patients were considered together, but this association was lost when the patients were classified into either near suppressed (0.1 ≤ TSH < 0.5) or suppressed (TSH < 0.1) TSH group. DiscussionAlthough the results suggest only a weak relationship with differentiated thyroid cancer, they strongly indicate that the DIO2 polymorphism influences the hormonal dose requirement in patients undergoing treatment with thyroxine. This probably points to a distinction in the way this gene influences disease as compared to therapy thereof.

Type 2 Deiodinase Thr92Ala Polymorphism Is Associated with a Reduction in Bone Mineral Density: A Community-Based Korean Genome and Epidemiology Study

Background: Type 2 deiodinase (DIO2)-mediated thyroid hormone synthesis stimulates osteoblast activity and increases the expression of osteoblast differentiation markers. Moreover, recent clinical studies identified a significant relationship between bone mineral density and thyroid hormone level in humans, but these studies had limitations that may have influenced their results, including small sample size, gender bias and enrollment of participants with specific diseases. Therefore, large cohort studies to identify the role of the DIO2 polymorphism in bone mineral density in humans are needed to provide additional information. Methods: To investigate the hypothesis that individuals with the DIO2 gene polymorphism are susceptible to osteoporosis, we assessed the polymorphism of the DIO2 gene in 7,524 Koreans drawn from the large-scale Ansan-Anseong cohort of the Korean Genome and Epidemiology Study (KoGES). Participants who were prescribed drugs that influence bone mineral density, those who provided insufficient information, and those with other diseases associated with osteoporosis were excluded from the study. All of the participants underwent genotyping of the DIO2 Thr92Ala polymorphism. We estimated the association of the DIO2 gene polymorphism with bone mineral density and other diverse clinical parameters using the chi-square test and ANOVA, and the risk of osteoporosis was determined using Cox regression analysis. Findings: A total of 6,022 participants were recruited; 1,991 (33.0%) were homozygous for the Thr allele, 2,967 (49.3%) were heterozygous (Thr/Ala), and 1,064 (17.7%) were homozygous for the Ala allele. The effects of the DIO2 Thr92Ala polymorphism on axial speed of sound (SOS) and the T-score in the tibia and radius were assessed, with age, gender, estrogen status, body mass index (BMI), serum calcium, 25-hydroxyvitamin D, and parathyroid hormone (PTH) included as covariables. Subjects carrying the DIO2 Thr92Ala polymorphism had consistently lower SOS and T-scores than heterozygous subjects. Additionally, female patients carrying the DIO2 Thr92Ala polymorphism had significantly lower SOS and T-scores than heterozygous participants. Cox regression analysis revealed a significant relationship between the DIO2 polymorphism and diagnosis of osteoporosis in female participants. Interpretation: We conclude that the DIO2 Thr92Ala polymorphism is associated with decreased SOS and T-scores in the tibia independent of other clinical parameters, where this indicates a potential functional role of DIO2 in the maintenance of bone mineral density. Funding Statement: This study was conducted with bioresources from the National Biobank of Korea, the Centers for Disease Control and Prevention, Republic of Korea (2018-022). This work was supported by the Korean Endocrine Society of New Faculty Research Award, 2018. Hyon-Seung Yi was also supported by the Basic Science Research Program, National Research Foundation, Ministry of Science and ICT, Future Planning, Korea (NRF-2018R1C1B6004439). Young Mi Kang and Yea Eun Kang were supported by the Basic Science Research Program, National Research Foundation, Ministry of Science and ICT, Future Planning, Korea (NRF2017R1D1A1B03027820). Declaration of Interests: All other authors declare no competing interests. Ethics Approval Statement: All subjects participated voluntarily and the study procedures were in accordance with our institutional guidelines and were approved by the Institutional Review Committee of the Korean National Institute of Health (CNUH-2018-03-028)

CGE19-062: The Rs1388378 Polymorphism in the Human DIO2 Gene is Associated with Decreased L-Thyroxine Dose Requirement in Thyroidectomized Patients

Background: Patients with differentiated thyroid cancer (DTC) are usually managed with total thyroidectomy and subsequent radioiodine ablation of the remnant thyroid tissue. L-thyroxine (L-T4) therapy (about 2 µg/kg) is required for life, with a wide variation in patient dose requirements. The iodothyronine deiodinase types I, II, and III (DIO1, DIO2, and DIO3, respectively) regulate the activity of the thyroid hormone via removal of specific iodine moieties from the precursor molecule T4. During LT4 replacement, the active hormone triiodothyronine (T3) levels strictly depend on DIO2-mediated activation of LT4. Therefore, the aims of this study were to investigate the association of DIO1 and DIO2 polymorphisms with DTC and L-T4 dose requirement in the Saudi population. Methods: A total of 1,067 (560 controls and 507 DTC thyroidectomized cases) Saudi Arabs were included. Serum free thyroxine and TSH levels were measured in the cases. We genotyped 1 DIO1 variant rs2294512_G and 3 DIO2 SNPs, rs1388378_T, rs12885300_T, rs225013_T, by TaqMan assay. Results: The DIO1 and DIO2 genotyping revealed an association between L-T4 dose requirement and rs1388378_T. Patients carrying the rs1388378_T allele required a lower l-T4 dose (145.91±33.31; P=.035). No significant association was found for these SNPs with cancer risk. Conclusions: Our study identified 1 DIO2 variant associated with L-T4 dose requirement. Thyroidectomized patients carrying T allele of rs1388378 need lower L-T4 dose to maintain normal TSH level thus providing evidence in favor of customized treatment of hypothyroidism in athyreotic patients.

Deiodinases, Organic Anion Transporter Polypeptide Polymorphisms, and Thyroid Hormones in Patients with Myocardial Infarction.

To investigate the association among deiodinases (DIO), organic anion-transporting polypeptide 1C1 (OATP1C1) gene polymorphisms, and thyroid hormones (THs) in patients with acute myocardial infarction (AMI). In summary, 290 patients with AMI were evaluated for sociodemographic and clinical characteristics, coronary artery disease (CAD) risk factors, and comorbidities, as well as circulating thyroid-stimulating hormone and TH (triiodothyronine [T3], thyroxine [T4], free T3, free T4, and reverse T3) levels. Ten single nucleotide polymorphisms for thyroid axis related genes: DIO1 (rs11206244-C/T, rs12095080-A/G, rs2235544-A/C), DIO2 (rs225014-T/C, rs225015-G/A), DIO3 (rs945006-T/G), and OATP1C1 (rs10444412-T/C, rs10770704-C/T, rs1515777-A/G, rs974453-G/A) were genotyped. Marginal associations were observed between the DIO1, DIO2, and OATP1C1 gene polymorphisms and almost all analyzed THs (p's < 0.05). After controlling for potential confounders, the OATP1C1 rs1515777-A/G minor allele homozygous genotype (G/G) was associated with a decrease in circulating free T3 and free T3/free T4. In the AMI cohort, associations between: DIO1 rs12095080 and hypertension; DIO2 rs225015 and diabetes mellitus; and the OATP1C1 rs974453 genotype, and AMI type were established. DIO1 and DIO2 gene polymorphisms are mainly associated with T3, free T4, free T3/free T4, and [natural-log transformed (ln)] reverse T3 levels, while the OATP1C1 minor allele homozygous genotype is associated with free T3 and free T3/free T4 in CAD patients after AMI.

A Common DIO2 Polymorphism and Alzheimer Disease Dementia in African and European Americans.

A common single nucleotide polymorphism in DIO2, Thr92AlaD2, has been associated with a transcriptome typically found in neurodegenerative diseases in postmortem human brain tissue. To determine whether Thr92AlaD2 is associated with incident Alzheimer disease (AD). Population-based study; human brain tissue microarray. Community-based cohorts from Chicago and northeastern Illinois and religious clergymen from across the United States constituted the primary population. A representative sample of the U.S. population was used for secondary analyses. 3054 African Americans (AAs) and 9304 European Americans (EAs). Incident AD. In the primary population, AAs with Thr92AlaD2 had 1.3 times [95% confidence interval (CI), 1.02 to 1.68; P = 0.048] greater odds of developing AD. AAs from a second population with Thr92AlaD2 showed a trend toward increased odds of dementia (odds ratio, 1.33; 95% CI, 0.99 to 1.78; P = 0.06) and 1.35 times greater odds of developing cognitive impairment not demented (CIND; 95% CI, 1.09 to 1.67; P = 0.006). Meta-analysis showed that AAs with Thr92AlaD2 had 1.3 times increased odds of developing AD/dementia (95% CI, 1.07 to 1.58; P = 0.008). In EAs, no association was found between Thr92AlaD2 and AD, dementia, or CIND. Microarray of AA brain tissue identified transcriptional patterns linked to AD pathogenesis. Thr92AlaD2 was associated with molecular markers known to underlie AD pathogenesis in AAs, translating to an observed phenotype of increased odds of developing AD/dementia in AAs in these populations. Thr92AlaD2 might represent one factor contributing to racial discrepancies in incident AD.

Increased anxiety and fear memory in adult mice lacking type 2 deiodinase

A euthyroid state in the brain is crucial for its adequate development and function. Impairments in thyroid hormones (THs; T3 or 3,5,3′-triiodothyronine and T4 or thyroxine) levels and availability in brain can lead to neurological alterations and to psychiatric disorders, particularly mood disorders. The thyroid gland synthetizes mainly T4, which is secreted to circulating blood, however, most actions of THs are mediated by T3, the transcriptionally active form. In the brain, intracellular concentrations of T3 are modulated by the activity of type 2 (D2) and type 3 (D3) deiodinases. In the present work, we evaluated learning and memory capabilities and anxiety-like behavior at adult stages in mice lacking D2 (D2KO) and we analyzed the impact of D2-deficiency on TH content and on the expression of T3-dependent genes in the amygdala and the hippocampus. We found that D2KO mice do not present impairments in spatial learning and memory, but they display emotional alterations with increased anxiety-like behavior as well as enhanced auditory-cued fear memory and spontaneous recovery of fear memory following extinction. D2KO mice also presented reduced T3 content in the hippocampus and decreased expression of the T3-dependent gene Dio3 in the amygdala suggesting a hypothyroid status in this structure. We propose that the emotional dysfunctions found in D2KO mice can arise from the reduced T3 content in their brain, which consequently leads to alterations in gene expression with functional consequences. We found a downregulation in the gene encoding for the calcium-binding protein calretinin (Calb2) in the amygdala of D2KO mice that could affect the GABAergic transmission. The current findings in D2KO mice can provide insight into emotional disorders present in humans with DIO2 polymorphisms.

DIO2 Thr92Ala Reduces Deiodinase-2 Activity and Serum-T3 Levels in Thyroid-Deficient Patients

A substantial proportion of athyreotic levothyroxine (LT4)-treated patients experience hypothyroid-like symptoms. During LT4 replacement, levels of the active hormone triiodothyronine (T3) strictly depend on type 2-deiodinase (D2)-mediated activation of LT4. The Thr92Ala polymorphism and the 258 G/A in the DIO2 gene have been associated with various clinical conditions. To investigate the effects of DIO2 polymorphisms in thyroid hormone homeostasis. We compared the presurgical hormonal status of thyroidectomized LT4-treated patients who had a similar thyroid-stimulating hormone (TSH) level with their postsurgery status and analyzed their DIO2 genotype in a subgroup of 102/140 (72.8%) of patients. We measured the enzymatic properties of Thr92Ala in living cells and in relevant generated mouse models. A total of 140 thyroidectomized subjects were included. Serum free T3 (FT3), free thyroxine, and TSH levels were directly measured. Immunohistochemistry and immunoblotting were performed for D2 protein. The DIO2 genotyping revealed an association between low FT3 values and Thr92Ala. Specifically, the mean postsurgery FT3 levels were significantly lower in patients carrying the mutated allele(s) than in wild-type patients, in whom FT3 postsurgical levels were similar to presurgery levels. The -258 G/A variation was not associated with hormonal alteration. We found that endogenous wild-type D2 and Thr92Ala share the same subcellular localization but differ in protein stability. Importantly, Thr92Ala reduced D2-mediated thyroxine to T3 conversion. Thyroidectomized patients carrying Thr92Ala are at increased risk of reduced intracellular and serum T3 concentrations that are not adequately compensated for by LT4, thus providing evidence in favor of customized treatment of hypothyroidism in athyreotic patients.

No effect of Thr92Ala DIO2 polymorphisms on thyroid parameters, health-related quality of life, and cognitive functioning

No effect of Thr92Ala DIO2 polymorphisms on thyroid parameters, health-related quality of life, and cognitive functioning

The rs225017 polymorphism in the 3'UTR of the human DIO2 gene is associated with increased insulin resistance.

The Thr92Ala (rs225014) polymorphism in the type 2 deiodinase (DIO2) gene has been associated with insulin resistance (IR) and decreased enzyme activity in human tissues but kinetic studies failed to detect changes in the mutant enzyme, suggesting that this variant might be a marker of abnormal DIO2 expression. Thus, we aimed to investigate whether other DIO2 polymorphisms, individually or in combination with the Thr92Ala, may contribute to IR. The entire coding-region of DIO2 gene was sequenced in 12 patients with type 2 diabetes mellitus (T2DM). Potentially informative variants were evaluated in 1077 T2DM patients and 516 nondiabetic subjects. IR was evaluated using the homeostasis model assessment (HOMA-IR) index. DIO2 gene sequencing revealed no new mutation but 5 previously described single nucleotide polymorphisms (SNPs). We observed that all T2DM patients displaying high HOMA-IR index (n = 6) were homozygous for the rs225017 (T/A) polymorphism. Further analysis showed that the median fasting plasma insulin and HOMA-IR of T2DM patients carrying the T/T genotype were higher than in patients carrying the A allele (P = 0.013 and P = 0.002, respectively). These associations were magnified in the presence of the Ala92Ala genotype of the Thr92Ala polymorphism. Moreover, the rs225017 and the Thr92Ala polymorphisms were in partial linkage disequilibrium (|D′| = 0.811; r 2 = 0.365). In conclusion, the rs225017 polymorphism is associated with greater IR in T2DM and it seems to interact with the Thr92Ala polymorphism in the modulation of IR.

Prevalence of Dio2(T92A) polymorphism and its association with thyroid autoimmunity.

The 3,5,3'-L-triiodothyronine (T₃) partly derives by the deiodination of the prohormone 3,5,3',5'-L-tetraiodothyronine (T₄) by the type 2 iodothyronine deiodinase (D2). The single-nucleotide polymorphism in the D2 gene at position 92 (Dio(2T92A)), generates an enzyme with a reduced T₄ to T₃ conversion velocity. Because thyroid hormones can modulate the immune response, we hypothesized a pathophysiological role for Dio(2T92A) polymorphism in autoimmunity. The objective of this study was to investigate the Dio(2T92A) polymorphism in relation to thyroid autoimmunity (TA). We compared the prevalence of Dio(2T92A) polymorphism and serum thyroid hormone levels in healthy subjects and subjects with TA. A total of 110 subjects with TA and 106 controls were genotypized for Dio(2T92A) polymorphism. Free T₃ (FT₃), free T₄ (FT₄) and TSH were measured and compared with the Dio(2T92A) polymorphism. Dio(292T/A), Dio(292A/A), and Dio(292T/T) healthy subjects were 40.9%, 46.4%, and 12.7%, respectively. These prevalences were similar to those of some European countries whilst significantly different from that of Brazil. In the two groups of healthy subjects and TA subjects, Dio(2T92A) polymorphism had a similar distribution with non-significant differences. Similarly, no significant differences were observed in the serum concentration of FT₃, FT₄, and TSH between subjects with different Dio(2T92A) polymorphism. The FT₄/FT₃, and TSH/FT₃ ratios were higher in Dio(292T/T) than in Dio(292T/A) and Dio(292A/A) subjects in both TA and healthy groups, but these differences were not significant. In conclusion, the distribution of Dio(2T92A) polymorphism may reflect geographical and ethnic differences, and it is not associated with TA.