Chronic lymphocytic thyroiditis and juvenile myxedema in uniovular twins

Graves' disease and Hashimoto's thyroiditis in monozygotic twins: case study as well as transcriptomic and immunohistological analysis of thyroid tissues

OBJECTIVE

To report on the rare simultaneous occurrence of Graves' disease (GD) and Hashimoto's thyroiditis (HT) in monozygotic twins.

DESIGN

We compared the pattern of thyroid tissue-derived cDNAs to gain insight into previous and ongoing immune destruction and reconstruction processes using microarrays. The results were confirmed by immunohistology and real-time PCR.

RESULTS

Destruction of thyroid tissue in HT reduced levels of thyrocyte-related cDNAs and cDNAs encoding extracellular matrix components, but increased levels of proteases involved in extracellular matrix degradation compared with GD. Lymphocytic infiltrates forming ectopic follicles replaced the thyroid tissue almost completely in HT. Thus, lymphocyte-related cDNA levels were higher in HT than in GD. The same was true for many chemokines and their receptors, which not only enable migration towards the thyroid but also maintain the lymphocytic infiltrate. HT also showed increased levels of cDNAs encoding molecules related to apoptosis than did GD. Surprisingly, the Th1- and Th2-specific cytokine profiles suggested for HT and GD respectively could not be confirmed. cDNAs encoding factors and receptors involved in angiogenesis were increased in GD compared with HT.

CONCLUSIONS

Comparison of gene expression reflects the cellular differences between the two types of autoimmune thyroid disease in twins with identical genetic and similar environmental background.

The genetics of Hashimoto's disease

Despite strong epidemiologic evidence in favor of a genetic component in the etiology of HT, few hereditary risk factors have been consistently identified. These factors include the HLA and CTLA-4 genes. The mechanisms by which these genes confer increased susceptibility to HT are unclear. The identification of these genes has failed to explain completely the large hereditary effect observed in families of patients. More substantial genetic determinants must be hidden in the folds of the human genome and will most likely be detected in the near future. The powerful approach of linkage analysis will be supported by advancements in the description of the human genome and by technologic improvements in the ability to process large amounts of biologic data. Knowledge of such determinants will provide predictive tools to be used on clinical grounds and invaluable insight into the pathogenesis of this puzzling disease.

A boy with atrophic thyroiditis of prepubertal onset, who was positive for TSH-binding inhibitor immunoglobulins

A 12 year old boy was admitted to our hospital because of short stature. From the age of 7, his growth velocity decreased and he manifested intolerance to low temperatures, hoarseness, dry skin, and slowness of thought and physical movement. On admission, his height was 129.8 cm (-3 s.d.) and his body weight was 43.2 kg (-0.5 s.d.). His clinical features also included relaxation phase of tendon reflexes, periorbital puffiness and cold skin but no struma. His bone age was 9 years. His serum thyroxine (T4), triiodothyronine (T3), free T4 and free T3 were low, while his thyrotropin was high. He was positive for antithyroglobulin antibodies, antimicrosomal antibodies, and TSH-binding inhibitor immunoglobulins. He was diagnosed as having atrophic thyroiditis. We also determined the HLA haplotypes of his family members. His father's HLA haplotypes were A2, BW61(a) and A24, BW52(b), while his mother's haplotypes were A24, BW52(c) and A30, BW60(d). The HLA haplotypes of both the patient and his younger brother showed a and d, while the patient's elder brother's HLA haplotypes showed b and c. His family members all had normal thyroid function, but his father was positive for antimicrosomal antibodies. In summary, we describe a rare case where the onset of hypothyroidism was prepubertal, where the pathogenesis may have involved TSH-receptor blocking antibodies, and where the inheritance of the disease may have been from the paternal side of the family.

Comparison of atrophic and goitrous auto-immune thyroiditis in children: clinical, laboratory and TSH-receptor antibody studies

We studied the clinical features, laboratory and thyroid functions and thyrotropin (TSH)-receptor and thyroid-stimulation antibodies in 21 patients with atrophic auto-immune thyroiditis (AAT) and 48 patients with goitrous auto-immune thyroiditis (GAT) of childhood onset. The clinical features of patient with AAT were cessation of growth and obesity, while asymptomatic enlargement of the thyroid gland was the sole symptom in most patients with GAT. Although the ages at diagnosis were comparable in both groups, the estimated ages at onset were much lower in patients with AAT than in those with GAT. Patients with AAT exhibited more severe hypothyroidism when evaluated by serum thyroxine (T4), tri-iodothyronine (T3), TSH, cholesterol levels and basal metabolic rates. The 24 h 123I-thyroidal uptake was significantly lower in patients with AAT than in those with GAT. None of the 19 patients with AAT possessed TSH-binding inhibitor immunoglobulins (TBII). On the other hand, 3 of the 32 GAT patients tested, possessed weak to potent TBII activities. Three TBII-positive patients with GAT also possessed thyroid-stimulation blocking antibodies. These findings suggest that: 1. Pathogenesis of AAT in children whose onset of hypothyroidism was before puberty is not due to TSH-receptor blocking antibodies, which are often found in patients with AAT of postpubertal onset. 2. AAT in children is considered not to be due to the later stage of GAT. 3. Some patients with GAT possessed TSH-receptor blocking antibodies. The aetiology and pathogenesis of AAT in children have yet to be elucidated.

Hyperthyroidism and hypothyroidism in monozygotic twins: detection of stimulating and blocking THS receptor antibodies using the FRTL5-cell line

We present a rare history of monozygotic twin girls who at the age of 10 yr presented with hyper- and hypothyroidism, respectively. Both girls had antibodies against thyrotropin receptors as measured by a radioreceptor assay (230 U/l and 1400 U/l; reference range less than 7 U/l). The sera were further examined in a bioassay, based on a rat thyroid cell line (FRTL5), in which release of cAMP into medium was measured. The TSH receptor antibodies of the hyperthyroid twin displayed a ratio of radioreceptor to biological activity typical of Graves' disease. In contrast, the antibodies of the hypothyroid twin acted as pure antagonists at the TSH receptor level. The occurrence of TSH receptor antibodies in these monozygotic twins suggests a similar pathogenesis of Graves' disease and that of hypothyroidism due to thyroid blocking antibodies.

Monozygous twins with hypothyroidism and diabetes mellitus

Monozygous twins with diabetes mellitus and autoimmune hypothyroidism are described. The onset of the hypothyroidism was simultaneous, but one twin had had insulin-dependent diabetes mellitus for 9 years while the other twin developed insulin-independent diabetes concurrently with the hypothyroidism. Two other siblings had diabetes mellitus and one of them had a goitre, possibly lymphadenoid. The aetiology of autoimmune hypothyroidism is discussed, and evidence is presented which supports suggestions that diabetes mellitus may be an autoimmune disease.

Autoimmune thyroid disease in children with mongolism

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