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Background and Aims This review aims to summarize current and emerging therapies for treatment of thyroid eye disease (TED), in the light of novel understanding of pathogenetic mechanisms, leading to new treatment options and clinical trials. Methods We reviewed and analyzed peer-reviewed literature reporting recent translational studies and clinical trials in the treatment of TED. Searches were made at www.pubmed.gov with keywords “thyroid eye disease,” “Graves’ ophthalmopathy,” “thyroid orbitopathy,” and “Graves’ orbitopathy.” Results Surgery is reserved for rehabilitation in chronic TED or for emergent compressive optic neuropathy. Oral and intravenous glucocorticoid therapy has been used for decades with variable efficacy in acute TED, but results may be temporary and side effects significant. Nonsteroidal oral immunosuppressive agents offer modest benefit in TED. Several immunomodulatory monoclonal antibodies, including rituximab and tocilizumab, have shown efficacy for inactivating TED. Recently, teprotumumab, an insulin-like growth factor 1 receptor (IGF-1R) inhibitor, has demonstrated significant improvement in proptosis, clinical activity score, diplopia, and quality of life in patients with active TED, with good tolerability. Newly proposed TED therapies, currently in preclinical and clinical trial phases, include thyroid-stimulating hormone (TSH) receptor inhibitory drugs, RVT-1401, local anti-vascular endothelial growth factor therapy, IGF-1R drugs delivered subcutaneously and orally, and desensitization to the TSH receptor with modified TSH receptor peptides. Conclusion New, albeit incomplete, understanding of the molecular mechanisms of TED has led to new promising therapies and offered improved outcomes in TED patients. Their full role and their relationship to classical immune suppression should be clarified over the next few years.

ContextThyroglobulin autoantibodies (TgAbs) affect thyroglobulin immunometric assays (TgIMAs), causing falsely low results. Conversely, heterophilic antibodies (HAs) may cause falsely elevated results. Thyroglobulin (Tg) measurements by mass spectrometry (MS) resist antibody interference. The most effective use of TgIMA/TgMS in the evaluation of Tg remains unclear.ObjectiveThe objective of this work was to study the usefulness of TgMS vs TgIMA in the presence of Tg measurement interference by HA and TgAb.MethodsIn 163 thyroid cancer patients, Tg was postoperatively measured by TgIMA and TgMS. When TgIMA was elevated and TgMS undetectable, HA was assessed by serial dilution and pretreatment with HA blocking reagent. TgIMA and TgMS were compared in TgAb-positive patients with well-characterized clinical status.Results6 out of 45 cases with TgIMA >1 ng/mL had undetectable TgMS. HA interference was confirmed by serial dilution and HA blocking reagent addition. In TgAb-positive cases, TgIMA and TgMS were highly correlated (R2 = 0.86). In patients with structural disease and TgAb, TgIMA and TgMS were detectable in 6/19 patients, and 9/19 cases, respectively. The TgMS concentration range in the 3 discrepant cases ranged from 0.5 to 2.0 ng/mL. Hence, the presence of TgAb was associated with inappropriately reduced Tg concentrations with both TgIMA and TgMS.ConclusionHA cause falsely elevated TgIMA with undetectable TgMS with significant frequency. TgMS can be used to rule out HA interference. Albeit resistant to TgAb in vitro, TgMS detects little Tg in patients with TgAb and structural disease. Hence, TgAb may reduce Tg concentrations in vivo. The implication is that no assay design may be able to overcome this problem. TgMS may not detect structural disease in TgAb-positive patients.

Objective To report a case series of thyroid cancer patients in whom false positive results in immunometric assays for thyroglobulin (TgIMA) were caused by heterophilic antibody interference, describe the clinical scenario in which this interference should be suspected, and recommend methods to demonstrate the interference. Methods Three patients with unexpectedly elevated thyroglobulin results (range, 1.6-75 ng/mL) were studied. In the first patient, thyroglobulin was elevated despite the presence of Tg antibody. In the second patient, suppressed thyroglobulin was higher than a recent stimulated thyroglobulin. In the third patient, thyroglobulin became detectable years after treatment and did not change after thyroid-stimulating hormone stimulation. TgIMA concentration determination was compared to determination by a mass spectrometry method (TgMS). Thyroglobulin was also remeasured after preabsorption with heterophile antibody blocking reagents and after serial dilutions. Results In all cases, thyroglobulin was undetectable by TgMS. In 2 of 3 patients, dilutions provided nonlinear thyroglobulin results. After blocking agent preabsorption, thyroglobulin dropped by 35%, 45%, and 91% in the 3 samples. Conclusion False positive thyroglobulin concentrations from heterophilic antibody interference have significant impact on the management of thyroid cancer. Here we show that TgMS assays can be used to rule out heterophilic antibody interference. This interference should be suspected when a detectable thyroglobulin by TgIMA does not respond to thyroid-stimulating hormone or is discordant from the clinical assessment.

Thyroid eye disease can be a debilitating autoimmune disorder characterized by progressive proptosis or diplopia. Teprotumumab has been compared with placebo in randomized clinical trials, but not with intravenous methylprednisolone (IVMP), which sometimes is used in clinical practice for this condition.To conduct a matching-adjusted indirect comparison of teprotumumab vs IVMP vs placebo.Deidentified patient-level data from teprotumumab trials and aggregate-level data from literature on the most recommended regimen of IVMP.PubMed and Embase were searched for randomized/observational studies using key terms and controlled vocabulary. Full texts of eligible articles were reviewed and cataloged.Conducted by 1 reviewer (R.A.Q.) and 1 verifier (R.B.), including study characteristics, eligibility criteria, baseline characteristics, and outcomes.Changes in proptosis by millimeter and diplopia response (percentage with ≥1 grade reduction) from baseline to week 12 in patients receiving IVMP and placebo, and to week 24 in patients receiving teprotumumab.The search identified 1019 records, and 6 through manual searches, alerts, and secondary references. After excluding duplicates and screening full-text records, 12 IVMP studies were included in the matching-adjusted indirect comparison (11 for proptosis change [n = 419], 4 for diplopia response [n = 125], and 2 teprotumumab [n = 79] and placebo [n = 83] comparator studies). Treatment with IVMP resulted in a proptosis difference of -0.16 mm (95% CI, -1.55 to 1.22 mm) from baseline to week 12 vs placebo. The proptosis treatment difference between IVMP and teprotumumab of -2.31 mm (95% CI, -3.45 to -1.17 mm) favored teprotumumab. Treatment with IVMP (odds ratio, 2.69; 95% CI, 0.94-7.70) was not favored over placebo in odds of diplopia response; however, teprotumumab was favored over IVMP (odds ratio, 2.32; 95% CI, 1.07-5.03).This meta-analysis suggests that use of IVMP is associated with a small, typically not clinically relevant, change from baseline in proptosis vs placebo, with modest changes in diplopia. While this nonrandomized comparison suggests that use of teprotumumab, compared with IVMP, is associated with greater improvements in proptosis and may be twice as likely to have a 1 grade or higher reduction in diplopia, randomized trials comparing these 2 treatments would be warranted to determine if 1 treatment is superior to the other to a clinically relevant degree.

Graves’ disease (GD) is an autoimmune disease that primarily affects the thyroid gland. It is the most common cause of hyperthyroidism and occurs at all ages but especially in women of reproductive age. Graves’ hyperthyroidism is caused by autoantibodies to the thyroid-stimulating hormone receptor (TSHR) that act as agonists and induce excessive thyroid hormone secretion, releasing the thyroid gland from pituitary control. TSHR autoantibodies also underlie Graves’ orbitopathy (GO) and pretibial myxoedema. Additionally, the pathophysiology of GO (and likely pretibial myxoedema) involves the synergism of insulin-like growth factor 1 receptor (IGF1R) with TSHR autoantibodies, causing retro-orbital tissue expansion and inflammation. Although the aetiology of GD remains unknown, evidence indicates a strong genetic component combined with random potential environmental insults in an immunologically susceptible individual. The treatment of GD has not changed substantially for many years and remains a choice between antithyroid drugs, radioiodine or surgery. However, antithyroid drug use can cause drug-induced embryopathy in pregnancy, radioiodine therapy can exacerbate GO and surgery can result in hypoparathyroidism or laryngeal nerve damage. Therefore, future studies should focus on improved drug management, and a number of important advances are on the horizon.

A variety of inflammatory disorders, generically classified as "thyroiditis," can affect the thyroid gland diffusely, generating distinctive radiographic patterns. While a precise diagnosis can seldom be made based on sonographic appearance alone, interpreting these patterns in the correct clinical and biochemical context will help support the most appropriate diagnosis. We believe that the generic term "thyroiditis" is often not helpful and often may be incorrect. Therefore, it is important for radiologists to understand the sonographic and functional correlations to provide the most appropriate differential diagnosis in their reports. This brief review is designed to provide information and guidance for radiologists when dealing with various thyroid disorders which cause diffuse changes in the thyroid and underline the pitfalls most often encountered in clinical practice.

Accurate immunoassays measuring minute quantities of hormones are the cornerstone of the practice of endocrinology. Despite tremendous advances in this field, novel pitfalls in these tests emerge from time to time. Oral biotin can interfere with immunoassays of several hormones. The purpose of this report is to relate an extreme case of such interference.A patient with progressive multiple sclerosis was found to have extremely elevated free thyroxine, triiodothyronine, and suppressed thyrotropin (TSH) levels. His TSH receptor binding inhibiting antibody level was also elevated. This constellation of laboratory findings suggested a diagnosis of severe Graves' disease. All of the assays yielding abnormal results employed the biotin-streptavidin affinity in their design. The patient had no symptoms of hyperthyroidism, and detailed review of his medications revealed intake of megadoses of biotin. Temporary discontinuation of biotin treatment resulted in complete resolution of the biochemical abnormalities.Non-physiologic biotin supplementation may interfere with several immunoassays, including thyroid hormones, TSH, thyroglobulin, and TSH receptor binding inhibiting antibody, leading to erroneous diagnoses. Questioning for biotin intake should be part of the evaluation for patients undergoing endocrine tests. Interruption of biotin supplementation for at least two days prior to biotin-sensitive tests should be sufficient to avoid major misdiagnoses.

Background: Thyroid hormones have significant effects on the cardiovascular systems. In general, hyperthyroidism is associated with an increased risk of dysrhythmias, while hypothyroidism may cause atherosclerosis. Recent large studies have sought to identify aging-associated changes in thyroid function and their relevance to cardiovascular morbidity and mortality in the elderly. Conflicting results have often been published, likely due to the heterogeneity of the studied populations. Objective: This review seeks to briefly summarize the most recent large population studies analyzing thyroid changes with aging and interpreting their effects on cardiovascular health in the elderly. Methods: Selective review of recent literature. Results: The emerging pattern suggests a slight decrease in thyroid function in the elderly leading to slightly higher thyroid stimulating hormone (TSH) levels. However, the incidence of mild hyperthyroidism also increases, especially in populations with historical or current iodine deficiency. Large observational studies suggest that the potential harm from mild hypothyroidism seen in younger population tends to diminish in older subjects, while the harm from mild hyperthyroidism becomes more significant. A markedly increased risk of atrial fibrillation is a well-established consequence of subclinical hyperthyroidism in patients in the sixth decade of life and beyond. Conclusions: The absence of large prospective interventional data does not allow the formulation of strict clinical recommendations, but a higher TSH threshold for treating both subclinical hypothyroidism and subclinical hyperthyroidism in the elderly seems reasonable.

Chronic lymphocytic thyroiditis (CLT), also known as Hashimoto thyroiditis, is an autoimmune disease characterized by lymphocytic infiltration of the thyroid gland, with the concomitant production of autoantibodies to thyroid antigens, primarily thyroglobulin and/or thyroperoxidase (TPO), formerly known as microsomal antigen (1). Although few epidemiological data are available, the prevalence of CLT is estimated to be 1 in 1,000 people, with an incidence of 0.2 to 2% and a female-to-male ratio of about 18:1 (1). Clinical signs and symptoms manifest slowly and may involve many systems of the body (1). Accumulations of hydrophilic mucoproteins with edema, a condition called myxedema, affects skin and connective tissue and can affect the appearance of the individual. Lethargy may ensue, with a loss of mental acuity. Systems commonly affected are the gastrointestinal tract, the hemopoietic system, the endocrine system, and the urogenital system (1). Enlargement of the thyroid gland due to lymphocyte invasion, called goiter, is a frequent manifestation, although there is an atrophic variation. Demonstration of autoantibodies to the thyroid antigens aids in the diagnosis of CLT, distinguishing it from other causes of hypothyroidism.

Radioactive iodine lobe ablation (RAI-L-ABL) is a possible alternative to completion thyroidectomy (C-Tx) for follicular thyroid carcinoma (FTC), but no long-term outcome data are available after lobe ablation. We analyzed the long-term outcome of lobe ablation in a series of patients with FTC.This was a retrospective study of patients who were treated with lobe ablation between 1983 and 2008. Of 134 patients with FTC, 37 (27.6%) had lobe ablation with (131)I (30-32 mCi) (RAI-L-ABL), 68 (50.7%) had C-Tx, and 29 (21.6%) had initial total thyroidectomy (T-Tx). The main outcomes analyzed were (131)I uptake after lobe ablation, C-Tx or T-Tx, serum thyroglobulin (Tg), serum thyroid-stimulating hormone (TSH), long-term disease-specific mortality, and disease-free survival.After lobe ablation, radioiodine uptake was significantly lower for the RAI-L-ABL group (0.6%) than for the C-Tx group (2.0%, p0.005) or T-Tx group (1.3%, p=0.054). Subsequent remnant ablation was performed in 12 of 37 (32%) patients in the RAI-L-ABL group, in 58 of 68 (85.3%) patients in the C-Tx group, and in 25 of 29 (86.2%) patients in the T-Tx group (p0.01). With median follow-up of 95 months for the RAI-L-ABL group, 47 months for the C-Tx group, and 53 months for the T-Tx group, there was one death in the RAI-L-ABL group and one death in the T-Tx group. No other RAI-L-ABL patients had detectable disease, whereas patients in the C-Tx group and two patients in the T-Tx group had detectable disease (p=0.18). Long-term stimulated or suppressed Tg of1 ng/mL were found in 87.5% of the RAI-L-ABL group (n=28), 86.3% of the C-Tx group (n=57), and 77.8% of the T-Tx group (n=21). Tg was detectable in 40.6% of the RAI-L-ABL group compared to 13.8% of C-Tx and 28.6% of T-Tx groups (p0.05, between groups).RAI-L-ABL, C-Tx, and T-Tx are equally effective in achieving serum TSH concentrations of25 mIU/L and preparing patients for conventional (131)I treatment and whole body scanning with similar long-term outcomes. However, persistent measurable Tg (range 0.2-2.2 ng/mL) is more common after RAI-L-ABL.

Acquired central hypothyroidism is rare, especially when isolated, and is typically associated with detectable, although biologically inactive, serum TSH.We describe a 56-yr-old woman with profound central hypothyroidism and partial central hypoadrenalism, in the absence of other endocrine abnormalities. In contrast to most cases of central hypothyroidism, serum TSH remained undetectable for 9 months before the initiation of thyroid hormone and hydrocortisone treatment. A test for pituitary autoantibody was moderately positive. Serum free T(4), serum T(3), and neck radioiodine uptake were low but detectable. The thyroid and pituitary glands appeared morphologically normal on neck ultrasound and head magnetic resonance imaging, respectively.The study was conducted in a tertiary academic medical center.This case illustrates the variable clinical presentation of pituitary autoimmunity. The persistence of low but detectable thyroid hormone levels and radioiodine neck uptake in the absence of TSH suggests that significant TSH-independent thyroid hormone synthesis may occur in the normal thyroid.

Over the years, several drugs used in the treatment of nonthyroidal conditions have been shown to affect thyroid function. As novel drugs are introduced, novel interactions are described. The aim of this review is to summarize clinically relevant thyroidal side effects of drugs used for nonthyroidal conditions. Special focus is given to recent developments and to drugs with the largest clinical relevance.Thyrosine kinase inhibitors are novel drugs used in the treatment of several neoplasias, including thyroid cancer. Thyroidal side effects are being increasingly detected with these drugs. Some drugs in this category affect thyroid hormone metabolism and therefore only affect patients on thyroid replacement. Others affect the thyroid directly profoundly, causing primary hypothyroidism. Immune modulators used in infectious, inflammatory, and neoplastic conditions also cause hyper- and hypothyroidism, through poorly understood immune or nonimmune mechanisms. The effects of amiodarone on the thyroid have been long recognized. However, given the complexity of these effects, several areas in this field remain problematic, such as the identification of subtypes of hyperthyroidism and the best treatment strategies. Lithium also has important antithyroid effects and it is a commonly prescribed medication. Its antithyroid effects may have clinical utility in selected clinical situations. Other drugs known to affect thyroid hormone absorption, metabolism, and transport are also briefly reviewed.Several drugs are known to alter thyroid function as a side effect of their primary pharmacological action. Some of these effects have been recognized for decades, but novel thyroid-drug interactions are being recognized as new drugs are developed. It is important for the clinician to be familiar with thyroid-drug interactions, as enhanced surveillance may be necessary in patients undergoing therapies known to affect thyroid function.

Describing common and uncommon manifestations of hypothyroidism and rapid changes in thyroid function.

Contains fulltext : 152088.pdf (Publisher’s version ) (Closed access) BACKGROUND AND PURPOSE: Thyroid diseases are common and often affect quality of life (QoL). No cross-culturally validated patient-reported outcome measuring thyroid-related QoL is available. The purpose of the present study was to test the cross-cultural validity of the newly developed thyroid-related patient-reported outcome ThyPRO, using tests for differential item functioning (DIF) according to language version. METHODS: The ThyPRO consists of 85 items summarized in 13 multi-item scales and one single item. Scales cover physical and mental symptoms, well-being and function as well as social and daily function and cosmetic concerns. Translation applied standard forward-backward methodology with subsequent cognitive interviews and reviews. Responses (N = 1,810) to the ThyPRO were collected in seven countries: UK (n = 166), The Netherlands (n = 147), Serbia (n = 150), Italy (n = 110), India (n = 148), Denmark (n = 902) and Sweden (n = 187). Translated versions were compared pairwise to the English version by examining uniform and nonuniform DIF, i.e., whether patients from different countries respond differently to a particular item, although they have identical level of the concept measured by the item. Analyses were controlled for thyroid diagnosis. DIF was investigated by ordinal logistic regression, testing for both statistical significance and magnitude (DeltaR (2) > 0.02). Scale level was estimated by the sum score, after purification. RESULTS: For twelve of the 84 tested items, DIF was identified in more than one language. Eight of these were small, but four were indicative of possible low translatability. Twenty-one instances of DIF in single languages were identified, indicating potential problems with the particular translation. However, only seven were of a magnitude which could affect scale scores, most of which could be explained by sample differences not controlled for. CONCLUSION: The ThyPRO has good cross-cultural validity with only minor cross-cultural invariance and is recommended for use in international multicenter studies.

The cytotoxic T lymphocyte-associated antigen-4 (CTLA-4) gene on 2q33 is associated with autoimmune thyroid diseases (AITDs). Our earlier study in 56 families showed linkage of 2q33 to the presence of thyroid antibodies (TAbs). The goals of this study were to confirm the linkage of the 2q33 region to TAbs, to fine map this region, and study the ICOS gene. We performed a linkage study in an expanded data set of 99 multiplex AITD-TAb families (529 individuals). The highest two-point LOD score of 2.9 was obtained for marker D2S325 on 2q33. To fine map this locus, we genotyped 238 Caucasian AITD patients and 137 controls for five additional markers in the linked locus, which contained the CTLA-4, CD28, and ICOS genes. The A/G single-nucleotide polymorphism at position 49 of CTLA-4 was associated with AITD (P=0.01, OR=1.5), while markers inside CD28 and ICOS were not. Functional studies have shown that the G allele was associated with reduced inhibition of T-cell proliferation by CTLA-4. We concluded that: (1) the AITD gene in the 2q33 locus is the CTLA-4 gene and not the CD28 or ICOS genes; and (2) the G allele is associated with decreased function of CTLA-4.

The autoimmune thyroid diseases (AITDs), comprising Graves disease (GD) and Hashimoto thyroiditis (HT), develop as a result of a complex interaction between predisposing genes and environmental triggers. Previously, we identified six loci that showed evidence for linkage with AITD in a data set of 56 multiplex families. The goals of the present study were to replicate/reject the previously identified loci before fine mapping and sequencing the candidate genes in these regions. We performed a whole-genome linkage study in an expanded data set of 102 multiplex families with AITD (540 individuals), through use of 400 microsatellite markers. Seven loci showed evidence for linkage to AITD. Three loci, on chromosomes 6p, 8q, and 10q, showed evidence for linkage with both GD and HT (maximum multipoint heterogeneity LOD scores [HLOD] 2.0, 3.5, and 4.1, respectively). Three loci showed evidence for linkage with GD: on 7q (HLOD 2.3), 14q (HLOD 2.1), and 20q (LOD 3.3, in a subset of the families). One locus on 12q showed evidence of linkage with HT, giving an HLOD of 3.4. Comparison with the results obtained in the original data set showed that the 20q (GD-2) and 12q (HT-2) loci continued to show evidence for linkage in the expanded data set; the 6p and 14q loci were located within the same region as the previously identified 6p and 14q loci (AITD-1 and GD-1, respectively), but the Xq (GD-3) and 13q (HT-1) loci were not replicated in the expanded data set. These results demonstrated that multiple genes may predispose to GD and HT and that some may be common to both diseases and some are unique. The loci that continue to show evidence for linkage in the expanded data set represent serious candidate regions for gene identification.

Many potential and willing living kidney donors are excluded from donating for a history of malignancy. There is appropriate caution toward patients with a history of malignancy because of concern for transmission of donor-derived malignancy. Thyroid cancer is common and increasing in incidence, and outcomes are very good in otherwise young, healthy potential donors. We review the evidence and guidelines regarding recurrence and transmission risk of thyroid cancer, and then we suggest a standardized guideline for otherwise healthy donors with a history of thyroid malignancy.

One of the hallmarks of the human autoimmune thyroid diseases (AITDs) is the production of high titers of autoantibodies against thyroglobulin and thyroid peroxidase that often precedes the development of clinical disease. A high percentage of family members of patients with AITDs have significant titers of thyroid antibodies (TAbs), suggesting a genetic predisposition for their development, and segregation analyses have favored a dominant mode of inheritance. The aim of the present study was to identify the susceptibility genes for TAb production. We completed a genome-wide scan in 56 multiplex families (323 individuals) in which all family members with AITDs and/or detectable TAbs were considered affected. The highest 2-point logarithm of odds (LOD) score of 3.6 was obtained for marker D2S325 on chromosome 2q33 at 210.9 centimorgans. This locus showed no evidence for linkage to Graves' disease or Hashimoto's thyroiditis (2-point LOD scores, 0.42 for Graves' disease and -0.60 for Hashimoto's thyroiditis), demonstrating that the gene in this region conferred susceptibility to TAbs, but that clinical disease development required additional genetic and/or environmental factors. We then fine-mapped the region linked with TAbs using 11 densely spaced microsatellite markers. Multipoint linkage analysis using these markers showed a maximum LOD score of 4.2 obtained for marker D2S155 at 209.8 centimorgans (with heterogeneity, alpha = 0.41). As the linked region contained the CTLA-4 and CD28 genes, we then tested whether they were the susceptibility genes for TAbs on chromosome 2q33. The CD28 gene was sequenced in 15 individuals, and a new C/T single nucleotide polymorphism (SNP) was identified in intron 3. Analysis of this SNP revealed no association with TAbs in the probands of the linked families (families that were linked with D2S155) compared with controls. The CTLA-4 gene was analyzed using the known A/G(49) SNP, and the results showed a significantly increased frequency of the G allele in the probands of the linked families compared with the probands of the unlinked families or with controls (P = 0.02). We concluded that 1) a major gene for thyroid autoantibody production was located on chromosome 2q33; 2) the TAb gene on chromosome 2q33 was most likely the CTLA-4 gene and not the CD28 gene; and 3) CTLA-4 contributed to the genetic susceptibility to TAb production, but there was no evidence that it contributed specifically to Graves' or Hashimoto's diseases.

The autoimmune thyroid diseases [Graves’ and Hashimoto’s diseases (GD and HT)] develop in genetically susceptible individuals, but the genes responsible for this susceptibility remain unknown. To identify such genes, we have been testing candidate genes and chromosomal regions using highly polymorphic microsatellite markers. We recently reported evidence for the first locus linked to GD (GD-1) on chromosome 14q31 in a small group of families. We have now extended these studies and analyzed 53 multiplex families with GD and/or HT (323 individuals). Chromosome 14 was screened using 16 microsatellite markers spanning the entire chromosome. Three additional markers located inside candidate genes on chromosome 14 were also studied. Microsatellite markers were amplified using fluorescent-labeled primers and separated on an ABI-310 genetic analyzer. The data were analyzed using LIPED software for two-point logarithm of odds (LOD) score analysis and GeneHunter software for multipoint linkage analysis. No linkage ...

Hashimoto's thyroiditis (HT) and Graves' disease (GD) are autoimmune thyroid diseases (AITD) in which multiple genetic factors are suspected to play an important role. Until now, only a few minor risk factors for these diseases have been identified. Susceptibility seems to be stronger in women, pointing toward a possible role for genes related to sex steroid action or mechanisms related to genes on the X-chromosome. We have studied a total of 45 multiplex families, each containing at least 2 members affected with either GD (55 patients) or HT (72 patients), and used linkage analysis to target as candidate susceptibility loci genes involved in estrogen activity, such as the estrogen receptor alpha and beta and the aromatase genes. We then screened the entire X-chromosome using a set of polymorphic microsatellite markers spanning the whole chromosome. We found a region of the X-chromosome (Xq21.33-22) giving positive logarithm of odds (LOD) scores and then reanalyzed this area with dense markers in a multipoint analysis. Our results excluded linkage to the estrogen receptor alpha and aromatase genes when either the patients with GD only, those with HT only, or those with any AITD were considered as affected. Linkage to the estrogen receptor beta could not be totally ruled out, partly due to incomplete mapping information for the gene itself at this time. The X-chromosome data revealed consistently positive LOD scores (maximum of 1.88 for marker DXS8020 and GD patients) when either definition of affectedness was considered. Analysis of the family data using a multipoint analysis with eight closely linked markers generated LOD scores suggestive of linkage to GD in a chromosomal area (Xq21.33-22) extending for about 6 cM and encompassing four markers. The maximum LOD score (2.5) occurred at DXS8020. In conclusion, we ruled out a major role for estrogen receptor alpha and the aromatase genes in the genetic predisposition to AITD. Estrogen receptor beta remains a candidate locus. We found a locus on Xq21.33-22 linked to GD that may help to explain the female predisposition to GD. Confirmation of these data in HT may require study of an extended number of families because of possible heterogeneity.

Graves’ and Hashimoto’s diseases are autoimmune thyroid diseases in which the genetic contribution is complex. For this reason, identification of necessary susceptibility genes has been difficult. However, a number of immunoregulatory genes have been implicated by association studies, including: CTLA-4, a recently described protein involved in antigen presentation, located on chromosome 2q33; the T-cell receptor Vα and Vβ gene complexes, located on 14q11 and 7q35, respectively; and the Ig gene complex (IgH), located on 15q11. We used polymorphic microsatellite markers located within these genes, or gene complexes, to test for linkage (rather than association), to each of these candidates. Using markers within the loci allowed us to assume a fixed recombination fraction of 0.01 in the tested model. Three hundred eight subjects from 48 multiplex families were studied, with 142 affected subjects. Using this set of families, we have previously shown evidence of linkage with a major susceptibility locus for Gr...

Graves' and Hashimoto's diseases are autoimmune thyroid diseases in which the genetic contribution is complex. For this reason, identification of necessary susceptibility genes has been difficult. However, a number of immunoregulatory genes have been implicated by association studies, including: CTLA-4, a recently described protein involved in antigen presentation, located on chromosome 2q33; the T-cell receptor V alpha and V beta gene complexes, located on 14q11 and 7q35, respectively; and the Ig gene complex (IgH), located on 15q11. We used polymorphic microsatellite markers located within these genes, or gene complexes, to test for linkage (rather than association), to each of these candidates. Using markers within the loci allowed us to assume a fixed recombination fraction of 0.01 in the tested model. Three hundred eight subjects from 48 multiplex families were studied, with 142 affected subjects. Using this set of families, we have previously shown evidence of linkage with a major susceptibility locus for Graves' disease (GD-1) on 14q24.3-31, with a maximum lod (logarithm + odds) score of 2.1, at a penetrance of 80% and with a dominant mode of inheritance. In the present study, we obtained consistently negative lod scores for each of the candidate genes, assuming either dominant or recessive modes of inheritance. These data, therefore, showed evidence against linkage with all the candidate genes. Unlike association studies, linkage analyses detect major genetic influences on disease susceptibility exerted by the linked loci. The lack of linkage for the immunoregulatory genes that were studied indicated, therefore, that they were not major contributors to disease etiology.

Myasthenia gravis (MG) may occur in association with autoimmune thyroid diseases (AITD). The aim of this study was to evaluate the features of MG associated with AITD compared to those of MG without AITD. A total of 129 MG patients (34 men and 95 women; age range, 11-81 yr) were subdivided into: group A, 56 MG patients with AITD [25 with autoimmune thyroiditis and 31 with Graves' disease (GD)]; group B, 21 MG patients with nonautoimmune thyroid diseases; and group C, 52 MG patients without thyroid disease. The severity of MG was ranked according to the Osserman score. Laboratory evaluation included assays for antithyroid and antiacetylcholine receptor (AchRAb) antibodies. Ocular MG (Osserman's class 1) was more frequent in group A (41.0%) than in group B (14.2%; P or = 2B) was more frequent in groups B (57.1%; P < 0.03) and C (51.9%; P < 0.02) than in group A (28.5%). GD patients with clinical evidence of ophthalmopathy had a higher frequency (P = 0.05) of ocular MG (57.8%) than GD patients without clinical ophthalmopathy (16.6%). Thymic disease was less frequent in group A (26.7%) than in group B (71.4%; P = 0.001) or C (59.7%; P = 0.001). The prevalence of thymic hyperplasia was 17.8%, 38.0%, and 40.3% in groups A, B, and C, respectively; the prevalence of thymoma was 8.9%, 33.4%, and 19.4%. When only patients with generalized MG were considered, thymic disease was less frequent (P < 0.02) in group A (40.6%) than in the remaining groups (69.4%). AchRAb was more frequent in groups B (57.1%) and C (57.6%; P < 0.03) than in group A (35.7%). In conclusion, MG associated with AITD has a mild clinical expression, with preferential ocular involvement and lower frequency of thymic disease and AchRAb. This supports the hypothesis that ocular and generalized MG are separate diseases with different spectra of associated diseases. Nonautoimmune thyroid diseases have no influence on the features of MG. The association of ocular MG and AITD might be due to a common autoimmune mechanism and/or a peculiar genetic background.

Fine-needle aspiration biopsy (FNAB) of the thyroid categorized as atypia of undetermined significance/follicular lesion of undetermined significance (AUS/FLUS) is a newly defined category according to the recent Bethesda guidelines. We sought to assess the characteristics and treatment of patients with an AUS/FLUS FNAB at our institution. Additionally, we evaluated the utility of the recommended 3-month timing of repeat FNAB.A retrospective study of all patients with an FNAB categorized as AUS/FLUS at an academic tertiary-care center. Clinical, cytological, and ultrasound variables were compared among management groups. Differences in patients receiving repeat FNAB before or after a 3-month interval were compared.A total of 203 patients of the 5,391 FNABs performed at our institution met the Bethesda criteria for AUS/FLUS; 62% were sent directly to surgery, 25% had a repeat FNAB, and 13% were observed. Younger (p=0.006) and male patients (p=0.04) were more likely to go directly to surgery. Microcalcifications, irregular margins, and marked hypoechogenicity on ultrasound did not appear to influence the decision to repeat the FNAB, observe the patient, or refer the patient for surgery. Timing of repeat FNAB (3 months or ≥3 months) did not alter the diagnostic results of the second FNAB (p=0.73). The overall rate of malignancy in patients undergoing surgery was 15.7%.Gender and age, not ultrasound characteristics, appear to influence the decision for surgery in AUS/FLUS patients. Timing of repeat biopsy did not alter management, repeat FNAB diagnosis, or rate of malignancy in our cohort.

Guidelines from the National Cancer Institute Thyroid Fine Needle Aspiration State of the Science Conference recommend a repeat fine-needle aspiration biopsy (FNAB) after 3 months for thyroid nodules with a nondiagnostic (ND) result. Our aims were to assess which factors influenced their clinical management and to determine if the timing of the repeat FNAB affects the diagnostic yield.A retrospective institutional review of 298 patients from 1/2006 to 12/2007 with an ND FNAB was performed. The factors influencing the next step in management, including age, gender, history of radiation, presence of Hashimoto's thyroiditis, thyroid-stimulating hormone levels, and ultrasound characteristics, were evaluated. The effect of the time of the repeat FNABs on their diagnostic yield was assessed.Of the 298 patients in our cohort, 9% were referred directly for surgery, 76% had a repeat FNAB, and 15% were observed. Tumor size was the only independent variable correlated with treatment strategy after a ND FNAB. There was not a significant difference in diagnostic yields between repeat FNABs performed earlier than 3 months compared to those preformed later (p=0.58).The timing of repeat FNAB for an initial ND FNAB does not affect diagnostic yield of the repeat FNAB.

Increased concentrations of serum soluble interleukin-2 (IL-2) receptor (sIL-2R), a marker of T-lymphocyte activation, have been found in several metastatic solid tumors. To our knowledge, no information is available on serum sIL-2R in differentiated thyroid carcinoma (DTC). Aim of this study was to evaluate whether disease activity and/or thyroid status may affect circulating sIL-2R in DTC, since it is has recently been demonstrated that serum thyroid hormone concentration positively modulates circulating sIL-2R. DTC patients were divided into 3 groups: Group A: 48 patients without metastases or local recurrences; Group B: 16 patients with cervical lymph node metastases; Group C: 22 patients with distant metastases. All patients were evaluated after total thyroidectomy both off and on L-thyroxine (L-T4) therapy. Control group was composed by 20 healthy euthyroid subjects. sIL-2R was assayed by solid-phase ELISA. In the hypothyroid state, sIL-2R levels of Group A were significantly lower when compared to normal controls (256±130 vs. 461±186 U/ml, p 910 U/ml) serum sIL-2R concentration off L-T4 therapy. No significant correlation between serum sIL-2R and serum thyroglobulin was observed both in hypothyroid (r=0.12, p=0.3) and in euthyroid (r=0.09, p=0.3) patients. No significant correlation was found between circulating sIL-2R and tumor histotype, duration of disease, previous amount of administered radioiodine and presence of antithyroid autoantibodies. In conclusion, the present study suggests that thyroid status and disease progression modulate serum sIL-2R. In patients free of disease, circulating sIL-2R appear to be strictly dependent on the thyroid status. In contrast, high serum sIL-2R was observed in some patients with metastatic DTC off L-T4 therapy, in spite of the hypothyroid state. This phenomenon is unrelated to several parameters of disease progression and its clinical meaning is unclear.

Paragangliomas in the region of the thyroid gland are rare tumors that can present a diagnostic challenge by mimicking follicular and c-cell derived thyroid tumors.Thyroid-associated paragangliomas are likely a subset of laryngeal paragangliomas and, although quite rare, should be considered in the differential diagnosis of a hypervascular thyroid nodule. The preoperative diagnosis of thyroid-associated paragangliomas can be challenging since the cytologic and histologic features overlap with more common primary thyroid neoplasms, in particular medullary carcinoma. Differential expression of a panel of immunohistochemical markers, including neuro-specific enolase, chromogranin A, synaptophysin, keratin, and S100, can be used to distinguish thyroid-associated paragangliomas from primary thyroid tumors. Intraoperatively, thyroid-associated paragangliomas may be associated with significant intraoperative bleeding and are often densely adherent to surrounding tissues, including the recurrent laryngeal nerve. Interestingly, the aggressive local behavior of these tumors does not correspond to potential for malignancy, as there are no patients with malignant thyroid-associated paragangliomas reported in the medical literature. Therefore, these tumors may be treated with limited resection. Postoperatively, patients with paragangliomas should receive hormonal evaluation for functional disease, imaging evaluation for multicentric and metastatic disease, and genetic counseling.Thyroid-associated paragangliomas are an important part of the differential diagnosis of a hypervascular thyroid nodule, especially in a patient with a fine-needle aspiration biopsy suggestive of medullary thyroid carcinoma, but with unremarkable serum calcitonin levels. Consideration of a thyroid-associated paraganglioma also has important operative and postoperative implications for determining the extent of thyroid resection as well as follow-up testing.

Graves’ disease (GD) results from an interplay of genetic factors and environmental triggers. We examined the immunoregulatory gene, Bruton’s tyrosine kinase (BTK), a candidate gene located in a region on chromosome Xq21.33−22 which we have previously found to be linked to GD and designated as GD-3. The study aimed to identify whether BTK was GD-3. No association was found between GD and alleles of the marker DXS178 and the A/C SNP. We concluded that BTK is not the GD-3 Graves’ disease susceptibility gene on chromosome Xq21.33−22.

Abundant epidemiological data point to a strong genetic susceptibility to the development of autoimmune thyroid diseases (AITD), Graves' disease (GD) and Hashimoto's thyroiditis (HT). However, identifying the AITD susceptibility genes has been confounded by significant genetic heterogeneity that exists in AITD. The goals of the present study were to dissect the genetic heterogeneity in AITD in order to identify novel AITD genes. We studied a dataset of 102 multiplex Caucasian AITD families (540 individuals) and divided them into three subsets: (1) families with young age of onset (AO ≤ 30), (2) families with females-only affected, and (3) Italian families. These subsets were analyzed separately for linkage with AITD in a whole genome screen. Four subset-specific loci were mapped: analyzing the families with AO ≤ 30, we identified a locus on 10q (linked with AITD) and a locus on Xp containing the FOXP3 gene (linked with GD); analysis of markers flanking the FOXP3 gene demonstrated association of one of the FOXP3 markers with juvenile GD in females (p = 0.02); in the subset of families with females-only affected the thyroglobulin (Tg) gene locus was linked with AITD; and in the Italian subset, a novel locus on 3q was linked with GD. Finally, applying the predivided-sample test confirmed that all four loci were specific to the subsets. We conclude that distinct genes predispose to AITD in different subsets of patients. We have identified four subset-specific AITD loci, and two putative subset-specific AITD susceptibility genes; the FOXP3 gene in juvenile GD and the thyroglobulin gene in females with AITD. In view of the significant genetic heterogeneity observed in AITD, analyzing subsets is an efficient way to resolve heterogeneity and identify novel genes.

The thyroid is a highly specialized endocrine gland, with the main function of producing thyroid hormones. It can be affected by several disorders, which either affect the process of hormone production or are neoplastic in nature, benign or malignant. In many of these disorders, a genetic predisposition has been recognized and studied. This article discusses the current knowledge on the heritability of thyroid disorders and the underlying genetic mechanisms.

Orbital radiotherapy is a well-established method of treatment for severe Graves' ophthalmopathy, because of its anti-inflammatory and locally immunosuppressive effects. It has been used for 60 years. Conventional external x-ray and cobalt therapy have been abandoned, and most groups now use supervoltage linear accelerators (4-6 MeV). Cumulative doses may vary, but in most studies a cumulative dose of 20 Gy delivered over 2 weeks was utilized. Successful outcome depends on the selection of patients, because recent onset, active ophthalmopathy is much more favorably affected than longstanding, inactive disease. Inflammatory signs, recent onset eye muscle dysfunction, and optic neuropathy respond well to orbital radiotherapy, while proptosis and longstanding eye muscle restriction respond poorly. Overall, favorable responses have been reported, with few exceptions, in approximately 60% of cases. Combination of irradiation with high-dose systemic glucocorticoids provides better results than either treatment alone. Orbital radiotherapy is well tolerated and safe. Preexisting retinopathy (e.g., in patients with diabetes) is a contraindication to this treatment for the risk of further retinal damage. No case of radiation-induced tumors has so far been described after orbital radiotherapy for Graves' ophthalmopathy.

The autoimmune thyroid diseases (AITD), Graves’ diseases (GD) and Hashimoto’s thyroiditis (HT) show a clear genetic component in epidemiological studies. The search for the genes responsible for the inheritance of the AITD has since many years provided evidence that some HLA haplotypes give a small, although significant contribution to the genetic susceptibility to the disease. Recently, the developments of the human genome-mapping project have provided the tools for whole genome scans. While this approach has yielded a number of loci of interest, precise definition of the genes at these loci is till under way. But the genome mapping efforts has also provided information on a number of new candidate genes, mainly immune response genes and thyroid autoantigens, that have been studied in both association and linkage studies for a possible involvement in AITD. To date only the cytotoxic T-lymphocyte antigen- 4 (CTLA-4) gene has emerged consistently as a second contributor to the genetic susceptibility to the AITD. CTLA-4 is an important down-regulator of the immune response and represents therefore an excellent candidate for autoimmunity. In this paper the current evidence for an involvement of the CTLA-4 gene in the genetic predisposition to AITD will be reviewed.

Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy is a rare autosomal recessive disorder characterized by hypoparathyroidism, adrenal failure, chronic mucocutaneous candidiasis, and ectodermal dystrophies and other organ-specific autoimmune diseases. Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy is caused by mutations of the autoimmune regulator gene. We identified an Italian family with autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy and a pattern of inheritance suggestive of a dominant mechanism. Serological and clinical studies showed a high prevalence of hypothyroid autoimmune thyroiditis in affected members with classical autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy. Direct sequencing of the entire coding region of the autoimmune regulator gene revealed the presence in the proband of a novel missense (G228W) mutation in exon 6 in a heterozygous state. The same heterozygous mutation was identified in all family members with autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy and/or hypothyroid autoimmune thyroiditis. None of the unaffected family members and 50 unrelated Italian controls carried the mutation. In contrast with all other autoimmune regulator mutations reported in families, the novel G228W mutation acts in a dominant fashion in our family, as only one heterozygous mutation was found in the entire coding sequence of the autoimmune regulator gene in the proband. Moreover, analysis of the family tree showed direct transmission of the hypothyroid autoimmune thyroiditis/polyendocrinopathy-candidiasis-ectodermal dystrophy phenotype to the offspring in each generation in the absence of consanguinity, further supporting a dominant inheritance. The G228W closely cosegregated with hypothyroid autoimmune thyroiditis in our family, whereas a low penetrance of the full autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy phenotype was observed. In conclusion, we report a novel mutation of the autoimmune regulator gene in a family with autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy, closely cosegregating with hypothyroid autoimmune thyroiditis. The G228W mutation acts in a dominant fashion and may shed light on the structure-function relationship of the autoimmune regulator protein.

To investigate the prevalence of thyroid autoantibodies in very old subjects, we assayed sera from 34 healthy centenarians (7 men, 27 women; age range 100-108 years) for these antibodies. There was a clear age-dependent increase in prevalence of thyroid autoantibodies in sera from 549 control subjects aged 7-85 years, prevalence in 40 subjects aged 70-85 being significantly greater (p less than 0.001, chi 2) than that in 436 subjects aged less than 50. By contrast, prevalence of thyroid autoantibodies in centenarians was not significantly different from that in controls aged less than 50. Cytofluorimetric analysis of peripheral blood lymphocytes showed a striking age-dependent decrease in total and CD5+B cells (without changes in their ratio), which reached its nadir in centenarians. The age-dependent increase in prevalence of thyroid autoantibodies in the elderly is not seen after the ninth decade of life. What relation this characteristic has to derangement of circulating B cells is unknown.

Graves' disease (GD) is an autoimmune thyroid disease (AITD) characterized by hyperthyroidism and by the occurrence of a distinctive ophthalmopathy (orbitopathy), which presents with varying degrees of severity. Graves' disease clusters in families but the importance of heredity in the pathogenesis of the associated ophthalmopathy is unclear. We have studied the family history of 114 consecutive, ethnically mixed patients with severe Graves' ophthalmopathy (GO). Patients were selected by unambiguous single ascertainment. Seventy-seven percent of patients were female and 59% smoked. The mean age at onset of their GD was 43 years (range 17-78 years). Forty-one patients (36%) had a family history of AITD, defined as a first- and/or a second-degree relative affected with either Graves' disease (GD) or Hashimoto's thyroiditis (HT). The segregation ratio for AITD in nuclear families in our ascertained Graves' ophthalmopathy families was 0.07 (0.12 in Caucasians only). Hence, the higher prevalence of AITD among relatives of Graves' ophthalmopathy patients agreed with the known genetic predisposition to AITD and this predisposition was stronger in women than in men. However, only 3 of the 114 patients had a family history of severe Graves' ophthalmopathy (all second-degree relatives) and the segregation ratio for GO was 0. These data did not support a major role for familial factors in the development of severe Graves' ophthalmopathy distinct from Graves' disease itself. In addition, we tested 4 candidate genes, human leukocyte antigen (HLA), tumor necrosis factor-beta (TNF-beta), CTLA-4 and the thyrotropin receptor (TSHR), for association with Graves' ophthalmopathy. These were negative except for the HLA and CTLA-4 genes, which were found to be weakly associated with GO giving similar relative risk (RR) as in GD patients without ophthalmopathy. These data suggested that environmental factors, rather than major genes, were likely to predispose certain individuals with AITD to severe Graves' ophthalmopathy. Smoking remains one example of such potential external insults.

Hashimoto's thyroiditis (HT), the prototype of chronic lymphocytic thyroiditis, is an inflammatory disorder of the thyroid gland characterized by an enlargement of the thyroid (goiter), lymphocytic infiltration of the gland, various degrees of thyroid hypofunction, and circulating antibodies to thyroid antigens. HT is an autoimmune disorder caused by an abnormal immune response to the thyroid gland, both of the humoral and cellular type. The observation that relatives of patients (index cases) are more likely to have the disorder than expected by chance indicates that a genetic predisposition to the disease exists. This view is supported by studies of spontaneous and experimental animal models of the disorder. Several candidate genes have been studied as predisposing factors. This article briefly reviews the evidence for a genetic component in the origin of the disease and summarizes the state of current knowledge on the genes involved.

Circulating thyroid autoantibodies were assessed in a sample of Italian octo-nonagenarians living in a restricted area (Val Vibrata, Abruzzo), and selected according to the absence or presence of chronic illness and disability. The study groups included: Group A ("Successful aging"), 98 free-living healthy, fully independent, octo-nonagenarians (57 males and 41 females, average age +/-SD 83.9+/-3 years); Group B ("Unsuccessful aging"), 62 highly disabled octo-nonagenarians (24 males and 38 females; average age 86.5+/-3.4 years), and Group C (Controls), 91 randomly selected healthy adult controls (42 males and 49 females; age 53.7+/-16.6 SD years, range 20-70). Serum autoantibodies to thyroglobulin (anti-Tg) and to thyroid peroxidase (anti-TPO) were measured by passive hemagglutination and radioimmunoassays (RIA); serum free thyroxine and thyrotropin by RIA. The prevalence of positive thyroid autoantibody tests was not significantly increased in the elderly groups compared to the controls, with the remarkable exception of anti-Tg detected by RIA which were increased in disabled elderly, compared to free-living elderly and controls. Two/62 disabled elderly had subclinical (1) or mild (1) primary hypothyroidism, and one free-living woman aged 90 years was hyperthyroid (toxic nodular goiter). No correlation was found between serum thyroid autoantibodies, thyroid hormones and TSH and serum lipoprotein fractions. The higher prevalence of thyroid autoantibodies found only in disabled, but not in free-living Italian octo-nonagenarians suggests that thyroid autoimmune phenomena in the elderly may be an expression of age-associated disease rather than related to the aging process in itself.

We previously showed that myasthenia gravis (MG) has a mild clinical expression when associated with autoimmune thyroid diseases (AITD). In the present study we have investigated the frequency of thyroid-associated ophthalmopathy (TAO) in patients with Graves' disease (GD) associated with MG as compared with GD patients without MG. A total of 418 patients with GD were studied, 31 with MG and 387 without MG. TAO was evaluated by physical examination, exophthalmometry, computerized tomography, and computerized visual fields assessment. The overall prevalence of TAO was similar in GD patients with MG (61.2%) and in those without MG (56.4%). When the analysis was restricted to GD patients with ocular MG, a greater frequency of TAO was found (84.6%), compared with GD patients without MG or with GD patients with generalized MG, although the differences did not reach the statistical significance. GD patients with MG had a significantly greater prevalence (12.9%) of euthyroid ophthalmopathy (clinically overt ophthalmopathy without previous and/or current hyperthyroidism) than those without MG (3.1%; p = 0.003). The results suggest a preferential association between the ocular manifestations of GD and MG, which may be due to immunological cross-reactivity against common autoimmune targets in the eye muscle as well as to a common genetic background.

The human autoimmune thyroid diseases (AITDs) are characterized by profuse infiltrates of both CD4+ and CD8+ T cells. The intrathyroidal T-cell-receptor repertoire in Graves' disease, more than in Hashimoto's disease, has been shown to be biased as evidenced by phenotypic analysis and by the use of a restricted T-cell-receptor variable (V) gene repertoire seen in both TCR alpha and beta chains. Evidence for a bias in the T-cell repertoire has also been observed in animal models of induced and spontaneous autoimmune thyroiditis. We found a similar phenomenon of autoimmune thyroid-related T-cell bias in thyroid-humanized scid mice. In these studies we transplanted lymphocyte-depleted thyrocytes and autologous peripheral lymphocytes from AITD patients with a basement membrane preparation which allowed the formation of an artificial thyroid which we have called an "organoid". T-cell clonal expansion was present in these artificial mixed-cell organoids which appeared to mimic the in vivo process. Such clonal expansion was suggestive of an antigen-driven immune response and could also be identified in thyroid tissue from patients with Graves' disease. Our data on scid mice grafted with human mixed-cell thyroid organoids, therefore, suggested that the major antigens driving T-cell selection in patients with AITD were most likely to be thyroid specific. These antigens include thyroglobulin, thyroid peroxidase, and the receptor for thyroid stimulating hormone (TSHR) on the surface of thyroid epithelial cells and we found significant T-cell proliferation to synthetic TSHR peptides in patients with AITD as compared with normals. Our search for a TCR recognition motif for the autoantigen TPO did not reveal any specific sequence motifs. Instead, analysis of the physico-chemical characteristics i.e. hydrophobicity of the amino acids in the CDR3 (N) region of the TCR alpha chain, revealed a strong negative linear correlation between strength of stimulation and the average hydrophobicity of N-region amino acids. This led us to hypothesize that lower affinity T-cell clones were commonly more hydrophobic in their CDR3 alpha region amino acids in keeping with potential crossreactivity of such T cells as a consequence of promiscuous, hydrophobic CDR3 regions. This phenomenon would be analogous to polyreactive, natural autoantibodies which tend to be crossreactive and 'sticky'. Thus, the physico-chemical characteristics of the TCR alpha CDR3 region supported the interaction with antigen/MHC by potentially cross-reactive T cells of low affinity. It would seem likely that such low-affinity autoreactive T-cell populations serve as a pool of potentially pathogenetic cells. These cells would be able to respond to an insult which, via a number of possible mechanisms such as molecular mimicry, would initiate a thyroid lymphocytic infiltration in an antigen-driven fashion with intrathyroidal T-cell expansion and a marked bias in the utilization of T-cell-receptor V genes.

The autoimmune thyroid diseases (AITD), encompassing Graves' disease (GD) and Hashimoto's thyroiditis (HT), occur in genetically susceptible individuals. In order to identify the AITD susceptibility genes, we have studied DNA markers in the regions of 8 candidate genes: (1) the HLA region, (2) the TSH receptor, (3) thyroid peroxidase, (4) thyroglobulin, (5) IDDM-4, (6) IDDM-5, (7) Immunoglobulin heavy chain gene and (8) CTLA-4. One hundred and seven subjects from 19 informative families were studied, 14 subjects had GD and 32 subjects had HT. LOD scores were maximized assuming both dominant and recessive modes of inheritance. No linkage was found for any marker in patients with HT. In patients with GD, negative LOD scores were obtained for all the candidate genes, except for markers in the TSH receptor region on chromosome 14q31. Positive LOD scores were found for several markers on 14q31. Marker D14S81 gave the highest score (Z max = 2.05, theta = 0.01) assuming a dominant mode of inheritance and a penetrance of 0.8. These data confirm our previous observations of a lack of a necessary disease locus for AITD in the HLA gene region. Further, the data suggest the presence of an important susceptibility gene on 14q31 but at a considerable distance from the TSH receptor gene.

Although medical genetics is a well-developed area of interest, relatively little is known about the diseases caused by the combination of many genes. These multiinfluenced diseases include the autoimmune endocrine diseases. Recent advances in the techniques for whole-genome screening have shown a variety of loci that are linked to the development of insulin-dependent diabetes mellitus, and similar data are likely to be soon generated in autoimmune thyroid disease. Here, the authors survey the current state of genetic knowledge in these two areas and describe the investigative and analytical techniques that are now available. (Trends Endocrinol Metab 1997;8:63–70). © 1997, Elsevier Science Inc.