[Peculiarities of formation, clinical presentations and therapy of diffuse nontoxic goiter of children]

The paper deals with the peculiarities of formation, clinical presentations and therapy of diffuse nontoxic goiter of children. The paper highlights the connection of the disease with the genetic predisposition, the impact of natural and anthropogenic strumagenes, immune processes. The clinical presentations of the diffuse nontoxic goiter are diffuse enlargement of thyroid gland, normal or high level of thyrotropichypophysis hormone when the content of thyroxin and triiodothyronine is normal, which is treated as the subclinic hypothyroidism syndrome. The variety of the disease pathogenesis theories leads to testing of different therapeutic methods, the principal ones among them are the use of iodine preparation and replacement therapy.

TSH regulates pendrin membrane abundance and enhances iodide efflux in thyroid cells

Thyroid hormones are essential for normal development and metabolism. Their synthesis requires transport of iodide into thyroid follicles. The mechanisms involving the apical efflux of iodide into the follicular lumen are poorly elucidated. The discovery of mutations in the SLC26A4 gene in patients with Pendred syndrome (congenital deafness, goiter, and defective iodide organification) suggested a possible role for the encoded protein, pendrin, as an apical iodide transporter. We determined whether TSH regulates pendrin abundance at the plasma membrane and whether this influences iodide efflux. Results of immunoblot and immunofluorescence experiments reveal that TSH and forskolin rapidly increase pendrin abundance at the plasma membrane through the protein kinase A pathway in PCCL-3 rat thyroid cells. The increase in pendrin membrane abundance correlates with a decrease in intracellular iodide as determined by measuring intracellular (125)iodide and can be inhibited by specific blocking of pendrin. Elimination of the putative protein kinase A phosphorylation site T717A results in a diminished translocation to the membrane in response to forskolin. These results demonstrate that pendrin translocates to the membrane in response to TSH and suggest that it may have a physiological role in apical iodide transport and thyroid hormone synthesis.

Absence of primary hypothyroidism and goiter in Slc26a4 (-/-) mice fed on a low iodine diet

BACKGROUND

Mutations in the SLC26A4 gene, coding for the anion transporter pendrin, are responsible for Pendred syndrome, characterized by congenital sensorineural deafness and dyshormonogenic goiter. The physiological role of pendrin in the thyroid is still unclear and the lack of a thyroid phenotype in some patients with SLC26A4 mutations and in Slc26a4 (-/-) mice indicate the existence of environmental or individual modifiers able to compensate for pendrin inactivation in the thyroid. Since pendrin can transport iodide in vitro, variations in iodide supply have been claimed to account for the thyroid phenotype associated with pendrin defects.

AIM

The Slc26a4 (-/-) mouse model was used to test the hypothesis that iodide supply may influence the penetrance and expressivity of SLC26A4 mutations.

MATERIALS AND METHODS

Slc26a4 (-/-) and (+/+) mice were fed up to 6 months on a standard or low iodine diet and were evaluated for thyroid structural abnormalities or biochemical hypothyroidism.

RESULTS

A 27-fold iodide restriction induced similar modifications in thyroid histology, but no differences in thyroid size, T4 or TSH levels were observed between between Slc26a4 (-/-) and (+/+) mice, either in standard conditions and during iodine restriction.

CONCLUSIONS

Iodide restriction is not able to induce a thyroid phenotype in Slc26a4 (-/-) mice. These experimental data, together with those coming from a review of familial Pendred cases leaving in regions either with low or sufficient iodide supply, support the idea that the expression of thyroid phenotype in Pendred syndrome is more powerfully influenced by individual factors than by dietary iodide.

Mutation analysis of SLC26A4 for Pendred syndrome and nonsyndromic hearing loss by high-resolution melting

Pendred syndrome and DFNB4 (autosomal recessive nonsyndromic congenital deafness, locus 4) are associated with autosomal recessive congenital sensorineural hearing loss and mutations in the SLC26A4 gene. Extensive allelic heterogeneity, however, necessitates analysis of all exons and splice sites to identify mutations for individual patients. Although Sanger sequencing is the gold standard for mutation detection, screening methods supplemented with targeted sequencing can provide a cost-effective alternative. One such method, denaturing high-performance liquid chromatography, was developed for clinical mutation detection in SLC26A4. However, this method inherently cannot distinguish homozygous changes from wild-type sequences. High-resolution melting (HRM), on the other hand, can detect heterozygous and homozygous changes cost-effectively, without any post-PCR modifications. We developed a closed-tube HRM mutation detection method specific for SLC26A4 that can be used in the clinical diagnostic setting. Twenty-eight primer pairs were designed to cover all 21 SLC26A4 exons and splice junction sequences. Using the resulting amplicons, initial HRM analysis detected all 45 variants previously identified by sequencing. Subsequently, a 384-well plate format was designed for up to three patient samples per run. Blinded HRM testing on these plates of patient samples collected over 1 year in a clinical diagnostic laboratory accurately detected all variants identified by sequencing. In conclusion, HRM with targeted sequencing is a reliable, simple, and cost-effective method for SLC26A4 mutation screening and detection.

High prevalence of TSHR/Gsα mutation-negative clonal hot thyroid nodules (HNs) in a Turkish cohort

Whereas the majority of hot thyroid nodules are caused by somatic TSH-receptor mutations, the percentage of TSH-receptor mutation negative clonal hot nodules (HN) and thus the percentage of hot nodules likely caused by other somatic mutations are still debated. This is especially the case for toxic multinodular goiter (TMNG). 35 HNs [12 solitary hot nodules (SHN), 23 TMNG] were screened for somatic TSHR mutations in the exons 9 and 10 and for Gsα mutations in the exons 7 and 8 using DGGE. Determination of X-chromosome inactivation was used for clonality analysis. Overall TSHR mutations were detected in 14 out of 35 (40%) HNs. A nonrandom X-chromosome inactivation pattern was detected in 18 out of 25 (72%) HNs suggesting a clonal origin. Of 15 TSHR or Gsα mutation negative cases 13 (86.6%) showed nonrandom X-chromosome inactivation, indicating clonal origin. The frequency of activating TSHR and/or Gsα mutations was higher in SHNs (9 of 12) than in TMNGs (6 of 23). There was no significant difference for the incidence of clonality for HNs between TMNGs or SHNs (p: 0.6396). Activating TSHR and/or Gsα mutations were more frequent in SHNs than in TMNG. However, the frequency of clonality is similar for SHN and TMNG and there is no significant difference for the presence or absence of TSHR and/or Gsα mutations of clonal or polyclonal HNs. The high percentage of clonal mutation-negative HNs in SHN and TMNG suggests alternative molecular aberrations leading to the development of TSHR mutation negative nodules.

Life-threatening metabolic alkalosis in Pendred syndrome

INTRODUCTION

Pendred syndrome, a combination of sensorineural deafness, impaired organification of iodide in the thyroid and goitre, results from biallelic defects in pendrin (encoded by SLC26A4), which transports chloride and iodide in the inner ear and thyroid respectively. Recently, pendrin has also been identified in the kidneys, where it is found in the apical plasma membrane of non-α-type intercalated cells of the cortical collecting duct. Here, it functions as a chloride-bicarbonate exchanger, capable of secreting bicarbonate into the urine. Despite this function, patients with Pendred syndrome have not been reported to develop any significant acid-base disturbances, except a single previous reported case of metabolic alkalosis in the context of Pendred syndrome in a child started on a diuretic.

CASE REPORT

We describe a 46-year-old female with sensorineural deafness and hypothyroidism, who presented with severe hypokalaemic metabolic alkalosis during inter-current illnesses on two occasions, and who was found to be homozygous for a loss-of-function mutation (V138F) in SLC26A4. Her acid-base status and electrolytes were unremarkable when she was well.

CONCLUSION

This case illustrates that, although pendrin is not usually required to maintain acid-base homeostasis under ambient condition, loss of renal bicarbonate excretion by pendrin during a metabolic alkalotic challenge may contribute to life-threatening acid-base disturbances in patients with Pendred syndrome.

The evaluation of argyrophilic nucleolar organizing region proteins in fine-needle aspiration samples of thyroid

Argyrophilic nucleolar organizing region associated proteins (AgNORs) have been shown to be of interest in a variety of different diseases including thyroid disorders. Our aim was to distinguish benign thyroid lesions from papillary thyroid carcinoma (PTC) via AgNOR count and with a new approach, via AgNOR surface area/total nuclear surface area (NORa/TNa) proportions in the nuclei on fine-needle aspiration (FNA) materials. Thirty patients (eight men and 22 women) whose FNA was compatible with benign lesion and 26 patients (eight men and 18 women) whose FNA was compatible with PTC were included in the study. Fine-needle aspiration materials were stained for AgNOR detection according to a specific protocol. One hundred nuclei per individual have been evaluated, and AgNOR number and NORa/TNa proportions of individual cells were measured and calculated by using a computer program. Patients with PTC had significantly (p<0.001) higher AgNOR count (4.6 ± 1.2%) than in the patients with benign lesions (2.0 ± 0.5%). Additionally, patients with PTC had significantly (p<0.001) higher NORa/TNa (13.4 ± 2.4) than in the patients with benign lesion (5.7 ± 1.0). Modified method of AgNOR staining is an easy and reliable method for evaluating proliferation activity of cells in malignant and benign thyroid lesions and it may contribute to routine cytopathology in inconclusive situations.

[Expression of BRAF V600E mutation in different thyroid lesions]

OBJECTIVE

To evaluate the expression of BRAF V600E mutation in 240 Chinese patients with thyroid lesions.

METHODS

Two hundred and forty Chinese patients with thyroid lesions, including 129 papillary thyroid carcinomas (PTC), 12 follicular carcinomas, 4 medullary carcinomas, 30 adenomas, 30 nodular goiters, and 35 papillary hyperplasia. DNA was extracted from thyroid biopsy and paraffin embedded thyroid tissues, and the expression of BRAF V600E mutation was detected by polymerase chain reaction and DNA sequencing assays.

RESULTS

The presence of BRAF V600E mutation was found in 61 of the total group of 240 cases (25.4%). It was only detected in PTC (47.3%), and not detected in other types of malignant and benign thyroid lesions. There was a statistically significant difference between the expression of BRAF V600E mutation in classic type PTC (49.6%) and in follicular type PTC (12.5%,P < 0.05), but statistical data did not show any correlation between BRAF V600E mutation and clinicopathologic parameters in PTC (P > 0.05).

CONCLUSIONS

BRAF V600E mutation has a significant correlation with PTC and the detection of BRAF V600E mutation may be used as an important prognostic marker of PTC. Our new method of DNA extraction from paraffin embedded tissues is efficient and inexpensive.

Hereditary hearing loss with thyroid abnormalities

Mutations in SLC26A4 can cause deafness and goiter in Pendred syndrome (PDS) or isolated non-syndromic enlargement of the vestibular aqueduct (NSEVA). PDS is one of the most common hereditary causes of deafness. It is characterized by autosomal-recessive inheritance of sensorineural hearing loss, enlarged vestibular aqueducts (EVA), and an iodide organification defect with or without goiter. The diagnosis is confirmed by detection of two mutant alleles of SLC26A4 in a patient with EVA. The perchlorate discharge test can detect the underlying thyroid biochemical defect and is useful for the evaluation of goiter or for the clinical diagnosis of PDS in a patient with a non-diagnostic SLC26A4 genotype. SLC26A4 encodes the pendrin polypeptide, an anion exchanger that, in recombinant expression systems, transports chloride, bicarbonate, and iodide. Investigation of pendrin function in the inner ear has been facilitated by the Slc26a4(Δ) (knockout) mouse model, but the exact mechanism of its hearing loss remains unclear, as does pendrin's principal transport function in the inner ear. Treatment of PDS is focused upon rehabilitation of hearing loss, and surveillance and management of goiter and, less commonly, hypothyroidism.

DICER1 mutations in familial multinodular goiter with and without ovarian Sertoli-Leydig cell tumors

CONTEXT

Nontoxic multinodular goiter (MNG) is frequently observed in the general population, but little is known about the underlying genetic susceptibility to this disease. Familial cases of MNG have been reported, and published reports describe 5 families that also contain at least 1 individual with a Sertoli-Leydig cell tumor of the ovary (SLCT). Germline mutations in DICER1, a gene that codes for an RNase III endoribonuclease, have been identified in families affected by pleuropulmonary blastoma (PPB), some of whom include cases of MNG and gonadal tumors such as SLCTs.

OBJECTIVE

To determine whether familial MNG with or without SLCT in the absence of PPB was associated with mutations in DICER1.

DESIGN, SETTING, AND PATIENTS

From September 2009 to September 2010, we screened 53 individuals from 2 MNG and 3 MNG/SLCT families at McGill University for mutations in DICER1. We investigated blood lymphocytes and MNG and SLCT tissue from family members for loss of the wild-type DICER1 allele (loss of heterozygosity), DICER1 expression, and microRNA (miRNA) dysregulation.

MAIN OUTCOME MEASURE

Detection of germline DICER1 gene mutations in familial MNG with and without SLCT.

RESULTS

We identified and characterized germline DICER1 mutations in 37 individuals from 5 families. Two mutations were predicted to be protein truncating, 2 resulted in in-frame deletions, and 1 was a missense mutation. Molecular analysis of the 3 SLCTs showed no loss of heterozygosity of DICER1, and immunohistochemical analysis in 2 samples showed strong expression of DICER1 in Sertoli cells but weak staining of Leydig cells. miRNA profiling of RNA from lymphoblastoid cell lines from both affected and unaffected members of the familial MNG cases revealed miRNA perturbations in DICER1 mutation carriers.

CONCLUSIONS

DICER1 mutations are associated with both familial MNG and MNG with SLCT, independent of PPB. These germline DICER1 mutations are associated with dysregulation of miRNA expression patterns.

Growth factor receptors gene expression and Akt phosphorylation in benign human thyroid nodules are unaffected by chronic thyrotropin suppression

Levothyroxine (L-T4)-based suppression of thyrotropin (TSH) secretion is widely used to prevent the growth of benign thyroid nodules, although the effectiveness of this approach has been demonstrated only in a subset of patients. In this study, we analyzed the in vivo effects of L-T4-mediated TSH suppression on elements of insulin/IGF-1-dependent growth-regulating pathways in tissues from patients with benign thyroid nodules. Nodular and non-nodular tissue specimens were collected from 63 patients undergoing thyroidectomy. 32 had received preoperative TSH suppressive therapy with TSH levels consistently below 0.5 mU/l (L-T4 group). TSH suppression had not been used in the other 31, and their TSH levels were normal (0.8-4 mU/l (control group). Quantitative RT-PCR was used to measure mRNA levels for TSH receptor, IGF1, IGF-1 receptor, insulin receptor, insulin receptor substrate 1 in nodular and non-nodular tissues from the 2 groups. Akt and phosphorylated Akt protein levels were detected by Western blot. Mean levels of mRNA for all genes tested were similar in the 2 groups, in both nodular and non-nodular tissues. The 2 groups were also similar in terms of phosphorylated Akt protein levels (measured by densitometric scan in 10 randomly selected nodules from each group). This is the first demonstration based on the study of human thyroid tissues that TSH suppression does not affect the expression of components of the insulin/IGF-1-dependent signaling pathways regulating thyrocyte growth. This may explain the lack of effectiveness of TSH-suppressive therapy in a substantial percentage of benign thyroid nodules.

Familial risks for hospitalized Graves' disease and goiter

OBJECTIVES

Familial clustering of a disease is an indicator of a possible heritable cause, provided that environmental sharing can be excluded. Thus, data on familial risks are important for genetic studies and for clinical genetic counseling.

DESIGN

We carried out a nationwide family study on nontoxic and toxic nodular goiters, and Graves' disease in order to search for familial clustering of these diseases at the population level.

METHODS

The Swedish Multigeneration Register on 0-75 year old subjects was linked to the Hospital Discharge Register from years 1987 to 2007. Standardized incidence ratios (SIRs) were calculated for offspring of affected parents and for siblings by comparing to those whose relatives had no hospitalization for thyroid disease.

RESULTS

The number of hospitalized patients in the offspring generations was 11 659 for nontoxic goiter, 9514 for Graves' disease, and 1728 for toxic nodular goiter. Familial cases accounted for 8.2, 5.2, and 2.1% of all patients respectively. The highest familial risk for offspring of affected parents was noted for Graves' disease (SIR 3.87), followed by toxic nodular goiter (3.37) and nontoxic goiter (3.15). Familial risks were higher for affected siblings: toxic nodular goiter (11.66), Graves' disease (5.51), and nontoxic goiter (5.40). Weaker familial associations were observed between the three diseases.

CONCLUSIONS

To our knowledge this is a first population-based family study on these thyroid diseases. The observed high familial aggregation for defined thyroid diseases cannot be explained by the known genetic basis, calling for further studies into genetic and environmental etiology of thyroid diseases.

Molecular aspects of the pathogenesis of nodular goiters, thyroid nodules and adenomas

One of the most significant results of recent molecular thyroid research on the pathogenesis of nodular goiters may be the finding that not only thyroid adenomas but also many thyroid nodules are clonal in origin and thus are true benign tumors. Both clonal and polyclonal nodules may coexist within the same nodular goiter. Since clonal nodules may secondarily acquire a heterogeneous phenotype, they can become morphologically indistinguishable from polyclonal lesions. The molecular mechanisms that generate thyroid nodules and adenomas are still poorly understood. Certainly, the recent detection of activating mutations in the TSH receptor and the Gs alpha gene in a subset of toxic thyroid adenomas and nodules may explain the generation of hyperfunction in these tumors, but there is strong evidence that these mutations are not the unique and primary cause of tumor formation. In this respect the concept of natural occurring heterogeneity of thyroid growth and function can provide a plausible explanation for the early stages of nodular transformation: If a thyrocyte has a high intrinsic growth potential or if it is affected by overexpression of a protooncogene or a growth factor or hit by an oncogene or other molecular events, the cell will outgrow and form a tumor. The inborn qualities of proliferating cells or the sequence of various genetic alterations in proliferating cells will in turn determine the phenotype and function of the tumor.

Constitutively activating TSH receptor mutations as the cause of toxic thyroid adenoma, multinodular toxic goiter and autosomal dominant non autoimmune hyperthyroidism

cAMP stimulates both the growth and differentiated thyroid function of the thyroid gland. In toxic nodules the clinical observation of hyperthyroidism together with TSH independent growth of the hot nodule suggests a chronic activation of the cAMP cascade. Somatic mutations in a gene of the cAMP regulatory cascade leading to constitutive activation of this cascade in toxic nodules were first detected in the G protein Gs alpha. Thereafter constitutively activating TSH receptor mutations were identified in 20-80% of toxic thyroid nodules and in 3 of 6 toxic multinodular goiters. Constitutively activating TSH receptor germline mutations are expected to lead to toxic hyperplasia. Sequencing of the TSH receptor gene in families with hereditary non autoimmune hyperthyroidism led to the identification of constitutively activating TSH receptor mutations in 7 families. Moreover, sporadic TSH receptor germline mutations have been identified in 3 children with severe congenital nonautoimmune hyperthyroidism. Therefore, in cases of clustering of non autoimmune hyperthyroidism in families and in cases of sporadic congenital hyperthyroidism with thyroid hyperplasia and no evidence for an autoimmune etiology a search for TSH receptor gene mutations is necessary to appropriately direct the therapy of these patients.

[Expressions of RASSF1A, Galectin-3 and TPO mRNA in papillary thyroid carcinoma and their clinical significance]

OBJECTIVE

To investigate the mRNA expressions of RASSF1A, Galectin-3 and TPO in papillary thyroid carcinoma and some other thyroid benign lesions, and evaluate their diagnostic significance.

METHODS

Reverse transcription polymerase chain reaction (RT-PCR) was used to detect the mRNA expression of RASSF1A, galectin-3 and TPO in the samples from 73 cases, including 23 cases with papillary thyroid cancer, 16 with nodular goiter, 29 with thyroid adenoma and 5 with Hashimoto's disease.

RESULTS

A statistically significant difference in the mRNA expression of RASSF1A, Galectin-3 and TPO was observed between papillary thyroid carcinoma and follicular benign lesions (P<0.05). However, there was no significant difference among various kinds of benign lesions (P>0.05). A negative correlation of the expression of RASSF1A and Galectin-3 mRNA was found between thyroid benign lesions and malignant ones (P = 0.000). While the mRNA expression of RASSF1A and TPO was positively correlated between benign and malignant lesions (P = 0.028).

CONCLUSION

Loss of expression of RASSF1A and TPO mRNA but high expression of Galectin-3 mRNA in papillary thyroid carcinoma are common. Therefore, the products of these three genes may be closely related to the development of thyroid papillary carcinoma, and may be used as useful markers in differential diagnosis of papillary thyroid carcinoma from the benign lesions. The results are more reliable if this detection method is used in combination with other techniques.

BRAFV600E mutation and X-linked inhibitor of apoptosis expression in papillary thyroid carcinoma

BACKGROUND

The BRAF mutation V600E (BRAF(V600E)) is the most common genetic alteration in papillary thyroid carcinoma (PTC), while overexpression of X-linked inhibitor of apoptosis (XIAP) has been found in various tumors. Both of these events are implicated in carcinogenesis, tumor progression, recurrence, etc. There are few reports, however, of the BRAF(V600E) mutation and XIAP overexpression in PTC patients. The aim of this study was to investigate the frequency of the BRAF(V600E) mutation in PTC and its relationship to clinicopathological parameters and the expression of XIAP.

METHODS

Genomic DNA was extracted from 123 paraffin-embedded PTC tumor tissue samples and amplified for analysis of the V600E mutation in exon 15 of the BRAF gene by polymerase chain reaction. XIAP expression was examined by immunohistochemical methods in 46 PTCs, 18 benign nodular goiters, and 10 Hashimoto's thyroiditis samples.

RESULTS

The BRAF(V600E) mutation was found in 34.1% of PTC, and was especially prevalent in the classic type. BRAF(V600E) was significantly correlated with younger age at diagnosis (p = 0.026), tumor size (p = 0.009), and histological variants (p = 0.024). There was a trend towards association with extrathyroidal invasion (p = 0.067). By logistic regression analysis, a significant relationship was found between tumor size and the BRAF(V600E) mutation (p = 0.03). XIAP was expressed in 82.6% of PTCs, which was a higher percentage than observed in the group of benign thyroid disorders (35.7%, p < 0.001). Neither the intensity (p = 0.611) nor the extent (p = 0.723) of XIAP staining was correlated with the presence of BRAF(V600E) in PTC patients.

CONCLUSIONS

These data indicate that BRAF(V600E) is associated some of the aggressive clinicopathological features of PTC including younger age at diagnosis, larger tumor size, and classic histological type, as well as also extrathyroidal invasion. XIAP-positive staining was more prevalent in PTCs than in the benign thyroid disorders. Although BRAF(V600E) and XIAP expression are commonly seen in PTC, their presence together seems unrelated.

1513A>C polymorphism in the P2X7 receptor gene in patients with papillary thyroid cancer: correlation with histological variants and clinical parameters

INTRODUCTION

The modulation of the purinergic receptor P2X7 may be implicated in human carcinogenesis. The 1513A>C and 489C>T polymorphisms of P2X7R gene induce loss of function and gain of function, respectively.

AIM

The aim of the study was to assess the frequency of both 1513A>C and 489C>T polymorphisms in patients with papillary thyroid carcinoma (PTC) and to evaluate the possible association with clinical and histological features.

PATIENTS AND METHODS

P2X7R analysis was performed in lymphocytes from 121 PTC patients (100 women, 21 men; aged 43.4 +/- 13.6 yr), 100 matched healthy subjects, and 80 patients with nodular goiter.

RESULTS

The minor allele frequency for 1513A>C polymorphism in PTC patients with the classical variant was similar to controls (0.21 and 0.20, respectively), whereas it resulted in a significant increase in patients with the follicular variant (0.36; P = 0.01 vs. classical variant, and P = 0.005 vs. controls). In detail, 13.6% of patients with PTC follicular variant were homozygous for the 1513C allele, compared to 2.6% of patients with the classical variant and 2% of controls. Moreover, a positive relationship between 1513A>C polymorphism and either cancer diameter (Rho = 0.22; P = 0.02) or TNM stage (Rho = 0.38; P < 0.001) was found. No significant difference in the genotype frequency of 489C>T polymorphism between PTC patients and healthy controls was observed (0.42 and 0.47, respectively).

CONCLUSIONS

Our data show, for the first time, a strong association between 1513A>C polymorphism of P2X7R gene and the follicular variant of PTC. Further studies are needed to confirm the possible role of this polymorphism as a novel clinical marker of PTC follicular variant and its usefulness in selecting patients with different clinical outcome.

Familial non-medullary thyroid carcinoma (FNMTC): analysis of fPTC/PRN, NMTC1, MNG1 and TCO susceptibility loci and identification of somatic BRAF and RAS mutations

Linkage analysis has identified four familial non-medullary thyroid carcinoma (FNMTC) susceptibility loci: fPTC/PRN (1p13.2-1q22), NMTC1 (2q21), MNG1 (14q32) and TCO (19p13.2). To date, there is no evidence for the involvement of genes from the RAS/RAF signalling pathway in FNMTC. The aim of our study was to evaluate the role of the four susceptibility loci, and RAS/RAF signalling pathway genes, in FNMTC. In total, 8 FNMTC families, and 27 thyroid lesions from family members (22 papillary thyroid carcinomas (PTCs): 11 classic, 10 of the follicular variant and 1 of the mixed variant; 4 follicular thyroid adenomas (FTAs) and 1 nodular goitre (NG)), were evaluated for the involvement of the four susceptibility regions, using linkage and loss of heterozygosity (LOH) analyses. BRAF and H-, N- and K-RAS mutations were also screened in the 27 lesions and patients. Linkage analysis in seven informative families showed no evidence for the involvement of any of the four candidate regions, supporting a genetic heterogeneity for FNMTC. Twenty tumours (74%), of which 18 were PTCs, showed no LOH at the four susceptibility loci. The remaining seven tumours (four PTCs, two FTAs and one NG) showed variable patterns of LOH. Fourteen tumours (52%) had somatic mutations: BRAF-V600E mutation was observed in 9 out of the 22 PTCs (41%); and H-RAS and N-RAS mutations were detected in 5 out of the 22 PTCs (23%). Our data suggest that the four candidate regions are not frequently involved in FNMTC and that the somatic activation of BRAF and RAS plays a role in FNMTC tumourigenesis.

Pendred syndrome in two Galician families: insights into clinical phenotypes through cellular, genetic, and molecular studies

CONTEXT

We studied two families from Galicia (northwest Spain) with Pendred syndrome (PS) and unusual thyroid phenotypes. In family A, the proposita had a large goiter and hypothyroxinemia but normal TSH and free T3 (FT3). In family B, some affected members showed deafness but not goiter.

OBJECTIVE

Our objective was to identify the mutations causing PS and molecular mechanisms underlying the thyroid phenotypes.

INTERVENTIONS

Interventions included extraction of DNA and of thyroid tissue.

PATIENTS

Propositi and 10 members of the two families participated in the study.

MAIN OUTCOME MEASURES

Main outcome measures included SLC26A4 gene analysis, deiodinase activities in thyroid tissue, and c.416-1G-->A effects on SLC26A4 splicing. In addition, a primary PS thyrocyte culture, T-PS2, was obtained from propositus B and compared with another culture of normal human thyrocytes, NT, by Western blotting, confocal microscopy, and iodine uptake kinetics.

RESULTS

Proposita A was heterozygous for c.578C-->T and c.279delT, presented with goiter, and had normal TSH and FT3 but low FT4 attributable to high type 1 and type 2 iodothyronine deiodinase activities in the goiter. Propositus B bore c.279delT and a novel mutation c.416-1G-->A; some deaf relatives were homozygous for c.416-1G-->A but did not present goiter. The c.279delT mutation was associated with identical haplotype in the two families. T-PS2 showed truncated pendrin retained intracellularly and high iodine uptake with low efflux leading to iodine retention.

CONCLUSIONS

c.279delT is a founder mutation in Galicia. Proposita A adapted to poor organification by increasing deiodinase activities in the goiter, avoiding hypothyroidism. Lack of goiter in subjects homozygous for c.416-1G-->A was due to incomplete penetrance allowing synthesis of some wild-type pendrin. Intracellular iodine retention, as seen in T-PS2, could play a role in thyroid alterations in PS.

Familial partial lipodystrophy due to the LMNA R482W mutation with multinodular goitre, extrapyramidal syndrome and primary hyperaldosteronism

Objective To describe new data about the wide phenotypic variability of diseases due to mutations in the lamin A/C gene (LMNA). Design We report a complex phenotype in a patient with familial partial lipodystrophy of the Dunnigan type (FPLD) and study the frequency of her unusual clinical signs in 19 other LMNA-mutated lipodystrophic patients from 8 different families and 14 non-mutated family members. Case Report The patient was diagnosed with FPLD due to the R482W LMNA mutation after familial screening. Surprisingly, she had no biological signs of insulin resistance. The presence of hypertension with hypokalaemia led to the diagnosis of primary hyperaldosteronism. Thyroid investigations showed a euthyroid multinodular goiter. In addition, the patient exhibited a juvenile akineto-hypertonic syndrome. Results Goiter was identified with a similar frequency (55%) in LMNA-mutated lipodystrophic patients (11 out of 20, originating from 5 families among 8) compared to non-mutated family controls (35%; 5 patients out of 14, all originating from the same family). No case of primary hyperaldosteronism or extrapyramidal syndrome was identified in other studied subjects, either LMNA-mutated or not. Conclusions This R482W-LMNA mutated patient showed an association of features (primary hyperaldosteronism, euthyroid goiter and extra-pyramidal syndrome, raising the question of a link with her laminopathy. Prevalence of goiter tended to be higher in LMNA-mutated than in non-mutated subjects. Hyperaldosteronism seems coincidental. Although extrapyramidal syndrome has never been reported in lipodystrophic patients, it may nevertheless be linked to the LMNA mutation since multiple neurological features have been associated with alterations in lamins A/C.

[Acral keratoses and inverted follicular keratosis presenting Cowden disease]

Cowden disease is a rare genetic disorder characterized by the presence of multiple hamartomas in the skin, thyroid, breast, nervous system and gastrointestinal tract. Mucocutaneous lesions are the most constant and characteristic finding. Breast and thyroid neoplasms (benign and malignant) develop in up to two thirds of patients. Inverted follicular keratosis as the presenting feature of Cowden disease is rare as the disease is usually suspected by the appearance of multiple facial trichilemmomas, oral mucosal papillomatosis and acral keratoses.

Peripheral blood levels of thyroglobulin mRNA and serum thyroglobulin concentrations after radioiodine ablation of multinodular goiter with or without pre-treatment with recombinant human thyrotropin

We investigated the effect of therapeutic doses of radioiodine (RAI) on peripheral serum messenger thyroglobulin RNA (Tg mRNA) and serum thyroglobulin (sTg) in patients with multinodular goiter (MNG) preceded or not by treatment with recombinant human TSH (rhTSH). Fourteen patients with large MNG (91-542 ml) received RAI (550-2960 MBq). Half of the patients received 0.45 mg of rhTSH prior to the treatment (RAI+rhTSH group) and half did not (RAI group). Patients' blood samples were collected before and 24, 48, and 72 h; 7 and 30 days; and 6, 9, and 12 months after RAI treatment. Serum Tg was measured by immunoradiometric assay, serum anti-Tg by radioimmunoassay, and quantification of circulating Tg mRNA was performed by real-time PCR. The shrinkage of MNG volume was documented by serial computed tomography (CT) scans before, 6 and 12 months after RAI. Peak Tg mRNA and sTg were reached earlier in the RAI+rhTSH group (24 h and 48 h) than in the RAI group (7 days). Both declined after the peak and the lowest levels were observed at 12 months. The mean reduction of the thyroid volume was 19.8% (RAI group) and 30.3% (RAI+rhTSH group) at 6 months (ns) and 32.8% RAI and 52.5% (RAI+rhTSH group) at 12 months (p<0.05). After RAI treatment there was a significant and positive correlation between goiter volume and sTg only in the RAI group (r=0.7; p=0.032). Serum anti-Tg had a transitory and relatively small elevation in 3 and 2 patients, respectively, in the RAI and RAI+rhTSH groups. We concluded that after RAI ablation of MNG there is a rapid release of Tg into the serum possibly from the colloid, which is followed by an elevation of serum Tg mRNA that may be due to an increased release of follicular cells into the blood stream. Both phenomena are enhanced by the use of rhTSH before RAI treatment as a consequence of a more effective and prolonged radiation exposure of the thyroid follicles.

H-RAS gene expression in human multinodular goiter

The RAS protooncogene has an important, although not yet established role in thyroid neoplasia. In this study, we evaluated the H-RAS mRNA and protein levels in human samples of nontoxic and toxic multinodular goiter samples, according to serum TSH levels. The mean of H-RAS mRNA levels in nodules of nontoxic nodular goiter were significantly increased compared to nonnodular tissue (1.49+/-1.21 vs. 0.94+/-0.81 AU, P=0.016). Nine of the 18 specimens (50%) of nontoxic multinodular goiter exhibited increased levels of H-RAS mRNA. The increased H-RAS mRNA levels were paralleled by inRAcreased H-Ras protein levels in about 90% of the cases. Interestingly, no differences were observed in H-RAS expression between nodules and adjacent nonnodular tissue in toxic nodular goiters (0.58+/-0.27 vs. 0.58+/-0.20 AU, P=0.88). None of the 10 samples from toxic multinodular goiters exhibited overexpression of H-RAS. The H-RAS expression was positively correlated with thyroglobulin expression (r2=0.51; P=0.04). In conclusion, we demonstrated increased levels of H-RAS mRNA and protein in samples of nontoxic multinodular goiter, indicating that it might be involved in goiter pathogenesis. In contrast, H-RAS overexpression was not detected in any of the samples of toxic multinodular goiter, suggesting different mechanisms for cell proliferation in nodular goiter according to thyroid status.

[The diagnostics of nodular goiter in children and adolescents]

The authors give an analysis of preoperative diagnostics of nodular tumors of the thyroid gland in 105 children and adolescents. It was shown that there are no special techniques allowing an absolute exclusion of malignant growth in the thyroid nodule before operation. The most accurate method of investigation in differential diagnostics of thyroid carcinoma in children and adolescents is thought to be fine-needle aspiration biopsy under USI control. The sensitivity of the method was 83.3%, the specificity - 98%.

Differential expression of miRNAs in papillary thyroid carcinoma compared to multinodular goiter using formalin fixed paraffin embedded tissues

microRNAs (miRNAs) are approximately 22 nt RNAs that negatively regulate target gene expression. Their dysregulation has been implicated in the pathogenesis of a number of human cancers, including papillary thyroid carcinoma (PTC). Whereas previous studies using microarray technologies have largely relied on the ability to procure fresh tissue at the time of surgery to characterize miRNA signatures in PTC, we exploited the ability to procure sufficient miRNA from formalin-fixed paraffin-embedded (FFPE) tissue to describe a series of miRNAs whose expression is dysregulated in PTC compared to benign proliferative multinodular goiter (MNG). We identified 13 miRNAs upregulated and 26 miRNAs downregulated in PTC versus MNG. These include miRNA-21, miRNA-31, miRNA-221, and miRNA-222. Their dysregulation was further validated by real time RT-PCR analysis in an independent set of FFPE tissues. Many of these have previously been described in fresh tissue studies as altered in PTC, confirming the utility of this approach. These results further highlight the applicability of miRNA expression patterns as potential markers of human cancer, and our results suggest that FFPE tissues are suitable resources for such miRNA expression analyses. The ability to utilize FFPE tissue in the molecular characterization of human malignancy will unlock a rich resource for future cancer studies.

[The expression of pseudogene HMGA1L2 in thyroid lesions]

Pseudogene HMGA1L2 mRNA level was detected using RT-PCR in 50 cases of thyroid lesions. The results show that HMGA1L2 mRNA was found in all 12 cases of nodular goiter, all 9 cases of thyroid adenoma and all 15 cases of papillary carcinoma. In 14 cases of thyroid follicular carcinoma, However, the frequency of HMGA1L2 mRNA expression was 35.7%, which was significantly different from that in other types of thyroid lesions (P < 0.05). This is the first report of mRNA expression of pseudogene HMGA1L2 in nodular goiter and thyroid tumors. It indicate that pseudogene HMGA1L2 expression analysis could be helpful in differentiation between follicular carcinoma and adenoma.

A new form of familial multi-nodular goitre with progression to differentiated thyroid cancer

We report a kindred with euthyroid multi-nodular goitre (MNG) of adolescent onset. Two of the seven subjects with MNG have progressed to papillary thyroid cancer. One affected male had nodular kidney disease, and breast cancer occurred in one affected female. Genes that were candidates on the basis of the associated kidney (PAX8) and breast diseases (sodium iodide symporter (NIS)), were sequenced. No mutations were found in the coding region, intron/exon splice sites or in the promoter sequences (from -1248 relative to the translation initiation codon) of PAX8. Similar results were obtained for NIS. Subsequently, microsatellite analyses were performed on 14 informative family members. We used 2 to 3 markers per locus for 6 loci (on chromosomes 1,2,3,14,19,X) previously reported to predispose to MNG and/or familial non-medullary thyroid cancer (FNMTC). On the basis of non-significant logarithm of the odds ratio (LOD) scores or inheritance of different alleles in affected individuals, all loci have been excluded. Thyroidectomy specimens from three members of the kindred show multiple benign lesions, with papillary cancer in two. The morphological features do not resemble those seen in familial adenomatous polyposis, Cowden syndrome, or in multiple oxyphil lesions. From these findings and from the absence of any linkage to any of the known loci associated with MNG or FNMTC, we suggest that this represents a new form of inherited MNG with a significant risk of progression to papillary carcinoma.

Congenital primary hypothyroidism with subsequent adenomatous goiter in a Turkish patient caused by a homozygous 10-bp deletion in the thyroid peroxidase (TPO) gene

OBJECTIVE

Congenital primary hypothyroidism occurs in 1 of 4000 births. Whereas the majority of the cases are due to developmental defects of the thyroid gland, 20% carry a defect in thyroid hormonogenesis. We report a Turkish boy who had goitrous hypothyroidism due to a mutation in the thyroid peroxidase (TPO) gene.

DESIGN

The TPO gene was sequenced directly from genomic DNA and cDNA which was transcribed from three RNA samples harvested from different parts of the patient's excised thyroid gland. Patient The boy was thyroidectomized because of continuing growth of his thyroid gland and development of multiple nodes suspected of malignancy by ultrasound examination. Histopathological examination verified a dyshormonogenetic goiter with multiple follicular adenomas.

RESULTS

The patient had a novel homozygous 10-bp deletion of the TPO gene at position 2812 in exon 16. This frame shift mutation results in a severely altered intracellular part of the protein. The deletion identified in leucocyte DNA was also found in thyroid tissue cDNA - so that instability of the transcript or a splicing defect was excluded. Both unaffected parents were heterozygous carriers of the mutation whereas 50 healthy individuals of the same ethnic background did not harbour the mutation.

CONCLUSIONS

The identified TPO gene deletion is the first mutation coding for an inactive TPO molecule, which has a severely altered intracellular segment. Because the most likely reason for the enlarging goiter was poor compliance of the patient, this report underlines the importance of a careful and regular follow-up of patients with dyshormonogenesis.

Prognostic significance of human pituitary tumor-transforming gene immunohistochemical expression in differentiated thyroid cancer

CONTEXT

Human securin pituitary tumor-transforming gene (hPTTG) is overexpressed in a variety of primary neoplasias, including differentiated thyroid cancer (DTC).

OBJECTIVE

The objective of this study was to examine the immunohistochemical expression of hPTTG in DTC and its association with known prognostic factors.

DESIGN

hPTTG expression was analyzed by immunostaining on paraffin-embedded tissues. Clinical data were used to determine any associations between the expression of hPTTG and prognostic variables of DTC. A median follow-up of 43 months allowed us to analyze the persistence of disease and the response to radioiodine therapy.

SETTING

The study was conducted at a tertiary university hospital.

PATIENTS

Ninety-five patients undergoing surgical resection for DTC (n = 60) or benign nodular thyroid disease (n = 35) were studied.

MAIN OUTCOME MEASURE

The main outcome measure was the association between hPTTG expression and prognostic factors in DTC.

RESULTS

Among DTC cases, 21 (35%) had low and 39 (65%) had high hPTTG immunostaining. Adjacent nonneoplastic thyroid tissue was largely unstained. Among benign nodular thyroid disease cases, immunostaining was detected focally in eight (22.8%). A significant association was found between hPTTG expression and the presence of nodal (P < 0.01) or distant metastases (P < 0.05). A significant association with TNM was also found, because 83.3% of advanced TNM stages showed elevated hPTTG (P < 0.05). The association between hPTTG overexpression and decreased radioiodine uptake during follow-up was also significant (P < 0.05). The expression levels of hPTTG were confirmed as an independent prognostic factor for persistent disease (relative risk, 3.0; 95% confidence interval, 1.1-8.7; P < 0.05).

CONCLUSIONS

Immunohistochemical analysis of hPTTG is of potential value in the determination of tumor aggressiveness in DTC.

Association of HLA DQ4-DR8 haplotype with papillary thyroid carcinomas

OBJECTIVE

The association of the human leucocyte antigen (HLA) system with thyroid carcinomas is not clear. We sought to relate HLA alleles to susceptibility to papillary thyroid carcinoma (PTC) and also to clinical and pathological characteristics of PTC patients.

DESIGN AND PATIENTS

The distribution of HLA in 181 unrelated Caucasian patients with PTC was compared to the HLA distribution in 315 normal controls, 31 patients with follicular carcinoma (FTC), 29 patients with lymphocytic thyroiditis (LT) and 50 patients with multinodular goitre (MNG), using a microlymphocytotoxicity assay.

RESULTS

Compared to normal controls, patients with PTC showed a significantly increased frequency of HLA-DQ4 [12.8%vs. 3.5%, P=0.0005, P(corrected) (P(c))=0.0032, odds ratio (OR)=4.058, 95% confidence interval (95% CI)=1.820-9.045] and HLA-DR8 (10.9%vs. 4.3%, P=0.013, P(c) > 0.05, OR=2.752, 95% CI=1.275-5.940). DQ4 and DR8 were also significantly increased in patients with MNG (DQ4, 16.3%; DR8, 16.3%) compared to controls (DQ4, P=0.0019, P(c)=0.011, OR=5.420, 95% CI=1.978-14.852; DR8, P=0.0044, P(c)=0.062). Linkage disequilibrium (LD) for these two alleles was present in controls (D=0.0130, P=9.7e-57) and in MNG patients (D=0.0730, P=4.6e-19) but not in PTC patients (D=0.038, P>0.05). In the subgroup of PTC subjects with concomitant 0thyroidal neoplasias (n=27), there was a significant (P< 0.05) increase in the frequency of B57 (18.5%), DR11 (56.5%) and DQ3 (81.8%) compared to PTC patients without coexistent neoplasias (2.0%, 21% and 47%, respectively). No significant differences of HLA allele distribution was found in relation to PTC histology, age at diagnosis (> 45 or <or45 years), gender or tumour-node-metastasis (TNM) staging. In patients with FTC, the frequency of DR17 (FTC=51.6%; controls =; P=0.0009; P(c)=0.0138) was significantly increased compared to controls. Patients with LT showed a higher frequency of the DR11 allele (48.3%) than controls (DR11=21.3%; P=0.0028, P(c)=0.039, OR=3.445, 95% CI=1.568-7.567).

CONCLUSIONS

We have typed the largest series of patients with thyroid carcinomas reported to date, and found that DR8 and DQ4 are independent susceptibility markers for PTC.

Associations of HLA-C Alleles With Multinodular Goiters

HYPOTHESIS

Several immunological alterations have been found in patients with multinodular goiter (MG). These alterations, together with the association described between certain autoimmune thyroid diseases and alleles of the major histocompatibility complex (HLA alleles), justify the need for studies of the HLA alleles and MG in an attempt to identify associations.

DESIGN

Case-control study.

SETTING

Tertiary referral center.

PATIENTS

Ninety consecutive patients underwent surgical procedures for MG. The control group comprised 100 unrelated, healthy, white subjects.

INTERVENTION

Genotyping for HLA-C alleles was done using the molecular biological technique of polymerase chain reaction using sequence-specific primers and was carried out for all of the patients.

MAIN OUTCOME MEASURES

The analyzed variables included age, sex, family history of thyroid pathological abnormalities, clinical features of the patient, clinical grading of the goiter, intrathoracic thyroid component, goiter weight, associated carcinoma, and the HLA-C gene.

RESULTS

A significant association was observed between the lower incidence of the HLA-Cw4 allele and the appearance of MG (15.5% vs 8.3%, respectively; P = .001; relative risk [RR] = 0.49). These results suggest that the HLA-Cw4 allele can exert a protective effect against MG. Analysis of the different clinical variables shows the most significant association to be the absence of the HLA-Cw4 allele in patients with goiters with an intrathoracic component (P = .001; RR = 0.19) and in patients with goiters weighing more than 200 g (P = .02; RR = 0.17). Associations between the HLA-C alleles and MG were also observed, such as the presence of the HLA-Cw7 allele and a family history of thyroid pathological abnormalities (P = .03; RR = 3.91) as well as the HLA-Cw1 allele and the presence of goiter-associated thyroid carcinoma (P = .02; RR = 8.60).

CONCLUSIONS

The HLA-Cw4 allele can act as a protector against the development of MG, as it occurs less frequently in the population with MG, and those with this allele develop smaller goiters with no intrathoracic component.

Lack of mutations in the TSHr and Gsalpha genes in TSHr antibody negative Graves' disease

The aim of this study was to investigate whether TSHr antibody negative Graves' disease is associated with somatic mutations in the TSHr or Gsalpha genes and whether histopathologically defined thyroid lesions, i.e., hyperfunctioning adenoma, non-functioning follicular adenomas, or nodules in toxic and non-toxic multinodular goiters are associated with such mutations. No mutations but three germ-line polymorphisms were found in patients with TSHr antibody negative Graves' disease. The three polymorphisms are expected to have no or only minor effects on the signaling properties, and is not associated with altered antigenecity imposed by such mutations. Two heterozygous somatic TSHr mutations were found in two hyperfunctioning adenomas and in two toxic multinodular goiters. The lack of TSHr and Gsalpha mutations in TSHr antibody negative Graves' disease patients indicates that such mutations are neither primary nor secondary events in this disease. The results also confirm that somatic gain-of-function TSHr mutations are present in hyperfunctioning follicular adenomas and goiters, but not in non-functioning thyroid lesions.

[SNP polymorphism of LGALS3BP gene in patients with benign and malignant thyroid tumours]

INTRODUCTION

The aim of the study was estimation of occurrence of SNP (single nucleotide polymorphism) sites in LGALS3BP gene in patients with benign and malignant thyroid tumors and analysis of correlation between their frequency and the histological type of thyroid lesions.

MATERIAL AND METHODS

The studied group consisted of 58 patients, 24 with papillary thyroid carcinomas, 19 with nodular goiters and 15 with follicular adenomas. Control group included 180 healthy volunteers. Four different SNP polymorphisms were analysed in PCR products using the SNaPshot test, on genetic analyser ABI Prism 310; these can be found in NCBI database under rs numbers: 1803938 (a/g), 11024 (g/c), 1801463 (a/c) and 1131516 (c/t).

RESULTS

In all patients analysis of SNP sites revealed: lack of polymorphism in a/g rs 18039380; polymorphism identical to database in g/c rs 11024 and polymorphism different from database in a/g rs 1801463 and c/g rs 131516. There were no significant differences between patients with thyroid lesions and group of healthy controls.

CONCLUSION

Single nucleotide polymorphism (SNP) of LGALS3BP gene (found in NCBI) database are not characteristic for papillary thyroid cancer, follicular adenomas and nodular goiter.

Mutations in the thyrotropin receptor signal transduction pathway in the hyperfunctioning thyroid nodules from multinodular goiters: a study in the Turkish population

Many studies have been carried out to determine G(s) alpha and TSHR mutations in autonomously functioning thyroid nodules. Variable prevalences for somatic constitutively activating TSHR mutations in hot nodules have been reported. Moreover, the increased prevalence of toxic multinodular goiters in iodine-deficient regions is well known. In Turkey, a country with high incidence rates of goiter due to iodine deficiency, the frequency of mutations in the thyrotropin receptor signal transduction pathway has not been evaluated up to now. In the present study, a part of the genes of the TSHR, G(s)alpha and the catalytic subunit of the PKA were checked for activating mutations. Thirty-five patients who underwent thyroidectomy for multinodular goiters were examined. Genomic DNAs were extracted from 58 hyperactive nodular specimens and surrounding normal thyroid tissues. Mutation screening was done by single-strand conformational polymorphism (SSCP) analysis. In those cases where a mutation was detected, the localization of the mutation was determined by automatic DNA sequencing. No G(s)alpha or PKA mutations were detected, whereas ten mutations (17%) were identified in the TSHR gene. All mutations were somatic and heterozygotic. In conclusion, the frequency of mutations in the cAMP signal transduction pathway was found to be lower than expected in the Turkish population most likely because of the use of SSCP as a screening method and sequencing only a part of TSHR exon 10.

Gene profiling identifies genes specific for well-differentiated epithelial thyroid tumors

Thyroid nodules are common. It would very helpful if genetic markers that can diagnose malignancy from fine needle aspiration samples were available. Few such markers has been thus identified and none are specific. Large panels of potential markers can be screened by microarray technology. Studies done to date have concentrated on single tumor types and thus provide no help in identifying tumor subtype specific markers. To that end we have studied gene profiles of 5 types of benign and malignant thyroid nodular tissue (multinodular goiter, follicular adenoma, papillary and follicular carcinomas). We have identified 195 genes whose differential expression clustered into clinically relevant groups. Twenty-eight genes were selected for further confirmation using real time quantitative polymerase chain reaction. Despite the differences in the microarray panels used, we confirmed the differential regulation of 12 genes previously reported in thyroid cancer, although we found the expression of several genes to be regulated in other histological tumor subtypes than originally described. We found, PCSK2, TRIB1, RAP1 GA1 to be specifically overexpressed in follicular cancer and S100A4 and GK2 in papillary carcinoma. SERP1, RNASE 2 and STATA5 were suppressed in papillary thyroid cancer. We have thus identified new potential markers specific to malignant thyroid tumors. It is apparent that a range of nodular thyroid tissue using large tumor sample numbers is necessary to establish robust markers for malignancy and to categorize tumors on the basis of small tumor samples.

Molecular pathogenesis of euthyroid and toxic multinodular goiter

The purpose of this review is to summarize current knowledge of the etiology of euthyroid and toxic multinodular goiter (MNG) with respect to the epidemiology, clinical characteristics, and molecular pathology. In reconstructing the line of events from early thyroid hyperplasia to MNG we will argue the predominant neoplastic character of nodular structures, the nature of known somatic mutations, and the importance of mutagenesis. Furthermore, we outline direct and indirect consequences of these somatic mutations for thyroid pathophysiology and summarize information concerning a possible genetic background of euthyroid goiter. Finally, we discuss uncertainties and open questions in differential diagnosis and therapy of euthyroid and toxic MNG.

Global DNA methylation evaluation: potential complementary marker in differential diagnosis of thyroid neoplasia

The implications of global DNA hypomethylation were recently reported in several models of tumorigenesis. Little is known about this epigenetic event in thyroid neoplasia. The study aimed to evaluate the status of global DNA methylation in several types of thyroid tumors using a monoclonal antibody specific for 5-methylcytidine (5-mc) and to define the diagnosis potential of this marker. 5-mc immunostaining scores were calculated in 17 papillary thyroid carcinomas (PTC), 6 follicular thyroid carcinomas (FTC), 16 follicular adenomas (FA), 19 nodular goiters (NG) and ten Hürthle cells adenomas (HCA). The expression of galectin-3 was also evaluated. Computerized image analysis showed a significant lower level of 5-mc immunostaining in thyroid carcinoma when compared with benign tumors or adjacent normal thyroid parenchyma (P<0.0001). Overall, 5-mc accuracy to distinguish malign from benign thyroid tumors was similar to that of galectin-3 (89% versus 87%, P>0.05). The combination of 5-mc with galectin-3 led to an excellent accuracy level of 96%. Among follicular neoplasia 5-mc accuracy to differentiate malign tumors trends to be higher than galectin-3 one (90% versus 66%, P=0.06). These data stress the necessity of epigenetic events evaluation among thyroid nodules and propose global DNA methylation assessment as a potential diagnostic tool to combine with other valuable markers.

CT of the Ear in Pendred Syndrome

PURPOSE

To prospectively determine the structural anomalies of the inner ear by using thin-section computed tomography (CT) in an extended family with Pendred syndrome.

MATERIALS AND METHODS

Ethics committee approved the study, and informed consent was obtained from every patient or from parents of patients under legal age. Twelve patients (three females and nine males aged 7-47 years) with Pendred syndrome (all from the same ethnic isolate and with the same mutation in the PDS gene) were evaluated for inner-ear malformation at thin-section CT. Both ears were evaluated. Presence or absence of interscalar septum between upper and middle turns of the cochlea was evaluated, and vestibule and vestibular aqueduct were examined for enlargement. Modiolus was determined to be present or absent (modiolar deficiency). CT scans were evaluated in consensus by two radiologists (M.G., J.M.G.).

RESULTS

All patients had inner ear malformation on both sides. Modiolus was absent and vestibule was enlarged on both sides in all 12 patients. Interscalar septum was absent in 18 (75%) of 24 ears. In eight patients, interscalar septum was absent in both ears, whereas in two patients, it was absent on only one side. Aqueduct was enlarged in 20 (80%) of 24 ears. In nine patients, both ears had enlarged aqueducts, while in two patients, only one side was abnormal.

CONCLUSION

Inner ear malformation is an invariable finding in Pendred syndrome. Modiolus deficiency and vestibular enlargement were the most consistent anomalies in this population with Pendred syndrome.

The novel missense mutation methionine 442 threonine in the thyroid hormone receptor beta causes thyroid hormone resistance: a case report

We report a family with thyroid hormone resistance caused by a novel mutation M442T in the thyroid hormone receptor beta (TRbeta) gene. The 59-year-old propositus and one of his two daughters had typical clinical signs of reduced responsiveness of tissues to thyroid hormones. Thus, elevated free T (3) and T (4) plasma concentrations in coexistance with a diffuse nodular goiter, nonsuppressed TSH, and atrial fibrillation with tachycardia were present in the propositus. His affected daughter also had increased levels of free T (3) and T (4) with slightly elevated TSH concentrations. Both affected members harboured a heterozygous M442T TRbeta mutation. The unaffected child had no mutation in the TRbeta gene and no clinical manifestations.

Die Knotenstruma. Die molekulare Entstehung - Konsequenzen für die Therapie?

Up to 15 % of the adult German population display an enlarged thyroid gland and up to 30 % present thyroid nodules. Iodine deficiency is the most important factor in the etiology of nodular goiter. Insulin-like growth factor-I is overexpressed in thyroids in severely iodine deficient areas. There is evidence that iodolactones are mediators of thyroid hormone autoregulation. However familial and twin studies demonstrated a genetic component in the etiology of nodular goiter. Linkage analysis identified two chromosomal regions (MNG-1, Xp 22) in multinodular goiter. Other possible candidate genes or markers such as TG, TPO, NIS, PDS and TSH-R were not identified. Nodular goiter certainly comprises a number of genotypes. TSH receptor mutations result in activation of the cAMP cascade. Cells with a constitutively activated cAMP cascade have an increased growth advantage due to their TSH independent cAMP stimulation. Alimentary iodine supply should be the first choice in primary prevention of nodular thyroid disease in iodine deficient areas, because prevalence of nodular goiter is negative correlated with individual iodine status in epidemiological surveys. Surgical removal of nodular goiters should include nearly the hold thyroid tissue to avoid recurrent goiter.

Autonomously functioning thyroid nodules in a former iodine-deficient area commonly harbor gain-of-function mutations in the thyrotropin signaling pathway

BACKGROUND

Somatic activating mutations of the thyrotropin (thyroid-stimulating hormone (TSH)) receptor (TSHR) and G(alphas) protein have been detected in solitary toxic adenomas and toxic multinodular goiters, but their role in the pathogenesis of autonomous nodules is debated. The frequency of mutations is highly variable among populations and is inversely proportional to iodine intake.

DESIGN AND PATIENTS

We screened 28 clinically and histologically heterogeneous autonomous nodules from 24 Greek patients for the presence of TSHR and G(alphas) mutations.

RESULTS

By direct sequencing of genomic DNA, we detected 11 somatic heterozygous gain-of-function mutations in TSHR and one in G(alphas). Forty-three percent (12 of 28) of all nodules and 57% (four of seven) of solitary toxic adenomas harbored an activating mutation. Typical adenomas and hyperplastic nodules did not differ in mutation frequency. Substitutions I568T and T632I were detected in both histological types of nodules.

CONCLUSIONS

Our findings indicate that activating somatic mutations in the TSH signaling pathway are frequent in autonomous nodules in Greece. This may be due to earlier exposure of the population to iodine deficiency, which was corrected in Greece only over the past two decades. Gain-of-function mutations are shared by nodules with varying histological and clinical presentations. Thus, they may represent a common molecular mechanism underlying the pathogenesis of non-autoimmune thyroid autonomy.

Assessment of microsatellite instability in bladder and thyroid malignancies

Microsatellite instability (MSI) is an indicator of a defective DNA mismatch repair system (MMR) that results from somatic mutations. The present work has been planned to investigate MSI and its clinical significance in human urinary bladder and thyroid cancers in Indian patients. Tumor tissues of histologically confirmed cases of urinary bladder and thyroid cancers, respectively, were obtained. Clinical data on tumor stage and histopathological grades were recorded. Corresponding matched peripheral blood was taken as a control. Genomic DNA was isolated from the tumor tissues and blood using a standard phenol-chloroform extraction method. Polymerase chain reaction was done to amplify mononucleotide microsatellite markers, BAT-26, BAT-40, TGFbetaRII, IGFIIR, hMSH3, and Bax by using specific primer sequences. For analysis of allelic patterns, the PCR products were run on 8% denaturing Polyacrylamide gel and sizing was done using a pUC18 sequencing ladder. The instability with BAT-26 and BAT-40 was found to be 20% and 45% in urinary bladder and 33% and 19% in thyroid cancers, respectively. However, no instability was observed with the other four-mononucleotide markers in either of the cancers studied. Eighty-three percent of the unstable urinary bladder cancers were found to have a high grade in a superficial group, whereas only 27% MSI+ve were muscle invasive cancers. Forty percent of unstable thyroid lesions were found to be at high risk of developing metastasis. Association of BAT-26 and BAT-40 instabilities with high grade tumors as well as risk tumors may help in choosing a more definite therapy at the outset.

Differential expression of mucins 1-6 in papillary thyroid carcinoma: evidence for transformation-dependent post-translational modifications of MUC1 in situ

Mucins are primary glycoproteins of epithelia that are known to undergo major changes in their post-translational processing during neoplastic transformation. This study has examined the expression pattern of seven primary mucins, ie mucin (MUC) 1, 2, 3, 4, 5AC, 5B and 6, in normal, hyperplastic, benign neoplastic, and papillary-type carcinoma (PTC) tissues of the thyroid. MUC1 and MUC5B were the only mucins to be widely transcribed in both benign and malignant tissues. In contrast, MUC4 transcripts were undetectable in normal thyroids, and were present in only 40% of the hyperplastic and malignant thyroid tissues. In PTC, MUC1 was identified as a single mRNA transcript, rejecting the idea that this mucin may undergo transformation-dependent alternative splicing in thyroid tumours. The tissue distribution of MUC1 and MUC4 proteins was highly heterogeneous: this largely paralleled their mRNA expression profiles and supported the conclusion that whereas MUC1 was ubiquitously expressed in PTC, MUC4 was detectable in less than 20% of the cases analysed. In order to determine whether post-translational modifications of MUC1, putatively associated with malignancy, also occurred in the mucin produced by PTC, immunohistochemistry was performed with a panel of well-characterized anti-MUC1 antibodies in conjunction with digestion of the tissue sections with deglycosylating enzymes. These experiments, which were supported by immunochemical analyses of the MUC1 and MUC4 glycoforms extracted from tissues, collectively demonstrated markedly divergent MUC1 glycosylation profiles in normal and benign thyroid tissues when compared with PTC. Characteristically, these latter neoplastic cells produced mucin molecules carrying complex poly-N-lactosamine-type glycans capped with fucose and neuraminic acid residues. The present study also found evidence in PTC for the potential presence of proteolytically processed MUC1 isoforms which differ in their post-translational traits depending on whether they are retained on the cell surface or secreted into the extracellular space. It is proposed that the observed differences in the glycosylation properties of normal and neoplastic MUC1 may be exploitable as an ancillary tool in the diagnosis of PTC.

Simian virus 40-like sequences from early and late regions in human thyroid tumors of different histotypes

Simian virus 40 (SV40) sequences were investigated in human thyroid tumors of different histotypes, Graves' disease thyroid specimens, normal thyroid tissues, and peripheral blood mononuclear cells (PBMC) of healthy donors. Specific SV40 large T antigen (Tag) sequences were detected, by PCR and filter hybridization, in human thyroid tumors with a frequency ranging from 66% in papillary thyroid carcinomas (PTC) to 100% in anaplastic thyroid carcinomas (ATC). SV40 was revealed in 60% and 100% of normal thyroid tissues adjacent to PTC and ATC, respectively, but in only 10% of control normal thyroid tissues (NTT) from patients affected by multinodular goiter. Thyroid tissues from patients affected by the Graves' disease were found to be SV40 positive with a frequency of 20%. In agreement with previous investigations, the presence of SV40 sequences was detected in 25% of PBMC of healthy individuals. SV40 Tag mRNA was detected by RT-PCR, whereas the viral oncoprotein was revealed by immunohistochemistry with a specific monoclonal antibody. The high prevalence of SV40 footprints in human thyroid tumors indicates that the oncogenic virus may participate as a cofactor in the onset/progression of specific human thyroid cancers. Detection of SV40 sequences in NTT adjacent to thyroid cancers suggests that the viral infection may spread from transformed cells to normal cells surrounding the tumor. The presence of the SV40 footprint in PBMC implies that blood cells are vectors of the virus in other tissues of the host.

Gain of function TSH receptor mutations and iodine deficiency: implications in iodine prophylaxis

Iodine deficiency is widely known to be the main cause of nodular goiter (NG). In iodine deficient areas subclinical and overt hyperthyroidism is the major cause of morbidity and it is mainly due to toxic NG rather than Graves' disease. Toxic NG, including toxic multinodular goiter and toxic thyroid adenoma is usually encountered in subjects with long-standing NG, in whom thyrotoxicosis is usually preceded by a long phase of euthyroidism and then subclinical hyperthyroidsm (abnormally low TSH with normal circulating thyroid hormones). Epidemiological studies indicate that, compared to Graves' disease, the incidence and prevalence of non-autoimmune hyperthyroidism due to toxic adenoma and toxic multinodular goiter differ in different regions of the world, being much more frequent in areas of iodine deficiency. Recently, mutations of the TSH receptor (TSHr) gene causing permanent activation of the thyroid follicular cell adenylate-cyclase, have been shown to be the most probable cause of the hyperfunction and growth of toxic adenoma. In this review we will focus our attention on the role of external factors (i.e. iodine deficiency) with respect to individual factors (i.e. genetic mutations) in the pathogenesis of toxic NG.

Lack of reported mutations in a Japanese case of toxic multinodular goiter

We describe a toxic multinodular goiter that was subjected to genomic sequencing of the thyroid-stimulating hormone receptor and the alpha-subunit of the stimulatory guanine nucleotide-binding protein. No mutation was detected in either gene. While frequent occurrence of thyroid-stimulating hormone receptor gene mutations in toxic multinodular goiters has been reported in areas such as part of Europe with a relatively high prevalence of iodine deficiency, toxic multinodular goiters in areas with an abundance of dietary iodine such as Japan seem unlikely to involve mutations of this gene.