Sumihisa Kubota

Association of the T-cell regulatory gene CTLA4 with Graves’ disease and autoimmune thyroid disease in the Japanese

AbstractAutoimmune thyroid disease (AITD) is caused by an immune response to self-thyroid antigen. The cytotoxic T-lymphocyte antigen-4 (CTLA4) gene, encoding a negative regulator of the T-lymphocyte immune response, had been reported to be associated and/or linked to AITD. Recently, AITD susceptibility in the Caucasians was mapped to the 6.1-kb 3′UTR of the CTLA4 gene, in which the three single-nucleotide polymorphisms (SNPs) CT60, JO31, and JO30 were strongly associated with AITD. In order to determine the association of the CTLA4 gene with AITD in the Japanese, case-control association analysis for the four SNPs of the CTLA4 gene using 380 AITD patients and 266 healthy controls was done. Among the SNPs examined, the SNP JO31 was most significantly associated with AITD in the Japanese, whereas the association of the JO30 with AITD was not observed. The frequency of the disease-susceptible G allele of the JO31 of the Japanese control was higher than that of the Caucasians (67.1% vs 50.2%); however, the G allele of the JO31 was associated with Graves′ disease (GD) (67.1% vs 76.3%, P=0.0013) and AITD in the Japanese (67.1% vs 74.2%, P=0.0055). Furthermore, the G allele of the JO31 was associated with the increased risk for GD [ P=0.0051, odds ratio (OR)=1.7] and AITD (P=0.016, OR=1.5) in a dominant model. These results suggested that the CTLA4 gene is involved in the susceptibility for GD and AITD in the Japanese.

Thyroid Function in Early Pregnancy in Japanese Healthy Women: Relation to Urinary Iodine Excretion, Emesis, and Fetal and Child Development

CONTEXT The effect of constant rich iodine intake, especially during pregnancy, has not been well understood. OBJECTIVE The objective was to examine urinary iodine excretion and thyroid function in early pregnancy in Japanese healthy women. We also studied fetal maturation and child development in these women. DESIGN AND SETTING This study was an observational, prospective study conducted at a maternity hospital. SUBJECTS Subjects were 622 pregnant women who visited a maternity hospital consecutively in early gestation. Subjects with positive thyroid antibodies were excluded, and finally 514 subjects were examined. Offspring subjects were infants born to the maternal subjects. MAIN OUTCOME MEASURES Thyroid function, serum thyroperoxidase antibodies, and urinary concentrations of iodine were measured at the initial obstetrical visit. The fetal maturation scores estimated by the Dubowitz and Ballard methods in newly born infants were assessed. A child developmental test was performed using the Enjoji Scale up to 12 months of age. RESULTS The distribution of urinary iodine concentrations was large, and the average was extremely high. There were significant positive correlations between urinary iodine and serum TSH (r = 0.1326; P < 0.005). Serum TSH during early pregnancy in mothers had no relevance to parameters in neonates, scores of fetal maturation, or child developmental testing in their infants. CONCLUSIONS Iodine excess during early pregnancy seems to have no adverse effects on the fetus in healthy Japanese women. To avoid hypothyroidism, reducing excess dietary iodine intake to moderate intake may be beneficial for pregnant woman in Japan.

Quantitative measurement of thyroid blood flow for differentiation of painless thyroiditis from Graves’ disease

Objective  Differentiation between destruction‐induced thyrotoxicosis and Graves’ thyrotoxicosis is important for selection of proper therapy. It is, however, often difficult to make this distinction without measurement of radioactive iodine uptake. We investigated the possibility that assessment of thyroid blood flow would allow differentiation between the two entities.

A Novel Homozygous Missense Mutation of the Dual Oxidase 2 (DUOX2) Gene in an Adult Patient with Large Goiter

OBJECTIVE To describe the first adult case of large goiter associated with a novel R1110Q mutation in the dual oxidase 2 (DUOX2) gene. She was initially euthyroid, and developed hypothyroidism later in her forties. DUOX2 is an essential enzyme in iodine organification of thyroid hormone biosynthesis. Only infant cases of congenital hypothyroidism due to mutations of the DUOX2 gene have been reported. Biallelic mutation of DUOX2 is thought to lead to total iodine organification defect. PATIENTS AND MEASUREMENT: This 57-year-old woman became first aware of goiter around the age of 20 years. Since the goiter had enlarged gradually, she consulted us at the age of 32 years. Goiter was soft, and thyroid function was normal. Antithyroid antibodies were negative. Both physical and mental development was normal. Three of her nine siblings and her mother had large goiters. At the age of 44 years, thyroid function demonstrated subclinical hypothyroidism. She started to take levo-thyroxine at a dose of 100 mug/day to reduce goiter. At the age of 56 years, goiter size remained the same. The perchlorate discharge rate was 72.8%, suggesting partial iodine organification defect. Thus, thyroid peroxidase (TPO) gene and DUOX2 gene were analyzed. RESULTS There was no mutation in the TPO gene, but a novel homozygous mutation (R1110Q) in the DUOX2 gene was identified. The same heterozygous mutation was detected in her two sons and two grandchildren. This mutation was not detected in 104 control alleles and was located at a site differing from any other reported mutations in the DUOX2 gene. CONCLUSIONS This homozygous missense mutation can be associated with thyroid dysfunction and goiter formation of an enlarged thyroid gland.

Serum concentrations of remnant‐like particles in hypothyroid patients before and after thyroxine replacement

objectives  Remnant‐like particles (RLPs) reflect chylomicron remnants and very‐low‐density lipoprotein remnants, which are most likely to be atherogenic particles. To investigate the effect of thyroxine replacement on the metabolism of RLPs in hypothyroidism, we measured serum concentrations of RLPs during an oral fat‐loading test in patients with hypothyroidism before and after thyroxine replacement.

Papillary Carcinoma Obscured by Complication with Subacute Thyroiditis: Sequential Ultrasonographic and Histopathological Findings in Five Cases

BACKGROUND Subacute thyroiditis (SAT) has been rarely reported to coexist with thyroid carcinomas. The objective of the study was to assess sequential ultrasonographic and histopathological findings of SAT in the context of complicating thyroid carcinomas. METHODS Of 1152 patients with SAT who visited our thyroid clinic at Kuma Hospital from 1996 through 2006, 5 cases complicated by papillary carcinoma underwent surgical resection 3-16 months after SAT onset. Ultrasonographic examinations and thyroid function tests were performed in all patients at onset of SAT and just before surgery. Sequential histopathological features of regenerated thyroid and carcinoma involvement were evaluated. RESULTS Heterogenous areas with microcalcifications in the thyroid or lymphadenopathy in three patients were clues for the nodular involvement with papillary carcinoma on the initial ultrasonographic examination. In contrast, diffuse hypoechoic change in the thyroid in two patients made it impossible to differentiate nodular involvement from inflammatory lesion. Histopathological examination of surgical specimens showed granulomatous and fibrotic changes. These were present about 3 months from SAT onset, and residual fibrosis remained several additional months, in the condition of no inflammatory hypoechoic lesions. In the areas of papillary carcinoma overlapping with transient inflammatory involvement, some lymphocytes and fibrotic changes were present in the stroma of papillary foci, but no granulomatous formation was present in any sections. Continuity with fibrosis around regenerated follicular cells was absent. The degree of lymphoid infiltrate and fibrotic change in the papillary carcinoma was not dependent on periods between SAT onset and the resection. CONCLUSIONS SAT may produce ultrasound changes that obscure the coexistence of papillary carcinoma, but affects no lymphoid infiltrate and fibrotic changes involved in carcinoma throughout the clinical course. We recommend that patients with SAT have ultrasonography after they recover. Further workup, including cytological examination of hypoechoic regions, should be performed if they are present as measuring 1 cm or larger.

Benefit of short-term iodide supplementation to antithyroid drug treatment of thyrotoxicosis due to Graves' disease.

Objective  Combined treatment with anti‐thyroid drugs (ATDs) and potassium iodide (KI) has been used only for severe thyrotoxicosis or as a pretreatment before urgent thyroidectomy in patients with Graves’ disease. We compared methimazole (MMI) treatment with MMI + KI treatment in terms of rapid normalization of thyroid hormones during the early phase and examined the later induction of disease remission.

Initial Treatment with 15 mg of Prednisolone Daily Is Sufficient for Most Patients with Subacute Thyroiditis in Japan

BACKGROUND Oral glucocorticoids are administered in moderate and severe cases of subacute thyroiditis (SAT), providing dramatic relief from pain and fever. However, there have been no reports regarding the optimal dose of prednisolone (PSL) for treatment of SAT. In this study, we used 15 mg/day of PSL as the initial dosage and tapered it by 5 mg every 2 weeks. We assessed the effectiveness of this treatment protocol. METHODS We examined 384 consecutive and untreated patients with SAT who visited our thyroid clinic between February 2005 and December 2008. We excluded patients who did not fit our protocol, and the final number of subjects was 219. When patients complained of pain in their neck or C-reactive protein (CRP) was still high, physicians were able to extend the tapering of the dose of PSL or increase it at 2-week intervals. The endpoint of the study was the duration of the PSL medication. We also compared the severity of thyrotoxicosis and rate of hypothyroidism after SAT between the short medication group (patients who recovered within 6 weeks) and long medication group (patients who recovered in 12 weeks or more). RESULTS The number of patients whose thyroiditis improved within 6 weeks and did not recur was 113 (51.6%), and 61 (27.9%) improved within 7 to 8 weeks and did not have a recurrence. The longest duration was 40 weeks. Seven patients (3.2%) needed increases in the dosage of PSL. Thyroid hormone (free thyroxine and free triiodothyronine) levels measured at the initial visit in the short medication group were significantly higher than those in the long medication group (p<0.05). Serum CRP, male-to-female ratio, body weight, and age showed no differences between the two groups. There were no differences in the rate of hypothyroidism after SAT between the two groups (p=0.0632). CONCLUSIONS The treatment protocol that we employed had 15 mg/day of PSL as the initial dosage for the treatment of SAT, with tapering by 5 mg every 2 weeks, and was effective and safe for Japanese patients. However, 20% of patients with SAT needed longer than 8 weeks to recover from the inflammation.

Identification of independent risk loci for Graves' disease within the MHC in the Japanese population.

To identify genetic variants that confer the risk of Graves’ disease (GD) in the Japanese population, we conducted a two-stage genome-wide association study (GWAS) using 1119 Japanese individuals with GD and 2718 unrelated controls, and a subsequent replication study using independent 432 GD cases and 1157 controls. We identified 34 single nucleotide polymorphisms (SNPs) to be significantly associated with GD in the GWAS phase. Twenty-two out of 34 SNPs remained positive in the replication study. All 22 SNPs were located within the major histocompatibility complex (MHC) locus on chromosome 6p21. No strong long-range linkage disequilibrium (LD) was observed among the 22 SNPs, indicating independent involvement of multiple loci within the MHC with the risk of GD. Multivariate stepwise logistic regression analysis selected rs3893464, rs4313034, rs3132613, rs4248154, rs2273017, rs9394159 and rs4713693, as markers for independent risk loci for GD. The analysis of LD between these seven SNPs and tagging SNPs for GD-associated human leukocyte antigen (HLA) alleles in the Japanese population (HLA-DPB1*0501 and HLA-A*0206) demonstrated that all of and five of seven SNPs were not in strong LD with HLA-DPB1*0501 and HLA-A*0206, respectively. Although causal variants remain to be identified, our results demonstrate the existence of multiple GD susceptibility loci within the MHC region.

Successful Management of a Patient with Pseudomalabsorption of Levothyroxine

Pseudomalabsorption of levothyroxine is a factitious disorder. Despite the administration of large doses of levothyroxine, patients with this disorder show hypothyroidism due to noncompliance. These patients are different from the patients with simple noncompliance in that they have a psychiatric disorder. Because their psychological identities are rooted in their being a “patient,” they go to great lengths to become and stay a patient. We report a case of pseudomalabsorption of levothyroxine. A 28-year-old woman was referred to us because she was believed to have unusual malabsorption of levothyroxine. We diagnosed the patient as having this factitious disorder, and as treatment, had her visit a hospital twice a week to take medicine under the observation of nurses so that she would not lose her status as a “patient.” Her serum free T4 level normalized during three years with twice weekly dosing of thyroxine after hospital discharge. Our approach could be a therapeutic choice for this intractable disorder. To our knowledge, this is the first report of successful management of a patient with pseudomalabsorption of levothyroxine.