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Barbesino et al., Pisa, Italy, and New York, NY, USA, performed whole
genome screening on a data set of 56 multiplex, multigenerational
families (354 individuals) with autoimmune thyroid disease
(AITD). They identified 5 loci that were linked with AITD. One
locus on chromosome 6 was linked to both Graves’ disease and
Hashimoto’s disease. Three loci on chromosomes 14, 20 and X
were linked with Graves’ disease but not with
Hashimoto’s disease. Another locus on chromosome 13 was
linked with Hashimoto’s disease but not with Graves’
disease. The results demonstrate that several genes contribute to
the inheritance of familial AITD and that the genetic
susceptibility to Graves’ disease and Hashimoto’s
disease is confirmed mostly by genes that are unique to each
disease, but also by common genes.
Strieder et al., Amsterdam, The Netherlands, assessed the prevalence of AITD in 1st and 2nd degree relatives of patients with Graves’ disease and Hashimoto’s hypothyroidism. A cohort of 1003 female relatives not known for thyroid disease was assembled. The prevalence of hypothyroidism was 9.1% (overt 1.5%, subclinical 7.6%). The frequency of TPO-Ab >100 kU/l and iodine excess was statistically higher in the hypothyroid then in the euthyroid subjects. The prevalence of hyperthyroidism was 1.9% (overt 0.3%, subclinical 1.6%). The frequency of TPO-Ab >100 kU/l was statistically higher but the use of oral contraception was statistically lower in the hyperthyroid than in the euthyroid subjects. In the euthyroid subjects with TPO-Ab >100 kU/l (n = 716) the use of oral contraception was statistically lower than those with TPO-Ab <100 kU/l (n = 77). The authors conclude that 1st and 2nd degree female relatives of AITD patients have a high prevalence of undetected AITD. Environmental factors like iodine excess and the use of oral contraception modified the risk of development of AITD in subjects at risk. (Comment: This important study implies that any subject who has a relative at least in the 1st or 2nd degree with AITD should be screened for thyroid autoimmunity and function as the prevalence of hypo- + hyperthyroidism is around 10%). Kurtev et al., Sophia, Bulgaria, studied the presence of AITD in 50 patients with Turner’s syndrome between the ages of 2 and 20 years. Goitre was present in 14/40 (40%) patients, subclinical hypothyroidism in 7/48 (15%) patients. Thyroid autoantibodies (Tg-Ab and TPO-ab) were positive in 21/41 (51%). Velluzzi et al., Cagliari, Italy, carried out a longitudinal study on both anti-thyroid autoantibodies (ATA) positive and ATA negative children from 2 Sardinian provinces with mild to moderate iodine deficiency. 801/3347 schoolchildren (23.6%) had goitre > OB (WHO criteria) and 88/3347 (2.6%) >1 (PAHO criteria). 120/3347 (3.6%) were ATA positive. After 4–9 years 65 ATA positive and 332 ATA negative were re-evaluated. The authors found a higher prevalence of large goitres in children showing persistence or appearance of ATA. However, a positive ATA or an isolated high TSH at screening was not associated with the development of significant thyroid dysfunction between 4 and 9 years. Even the combination of these two at screening was not followed by an increased rate of thyroid dysfunction. (Comment: These results are remarkable, in that studies in adults show that the presence of autoantibodies or a mildly limited TSH elevation with normal thyroid hormone parameters carries an increased risk in the development of overt hypothyroidism. This is even more pronounced when both abnormalities are present. It will be very interesting if the follow-up of these children could be continued into adulthood.) Latrofa et al., Pisa, Italy, followed a group of 138 patients after total thyroid ablation or differentiated thyroid carcinoma (DTC) with positive TPO-Ab and/or Tg-Ab (F = 151, mean age 38 years, range 6–81 years) with regard to any change in antithyroid antibodies. They also followed 54 patients (34 Hashimoto’s disease and 10 Graves’ disease) who had associated treated DTC. All patients were initially treated with total thyroidectomy + 131I therapy. Any metastases were treated either by 131I or surgery with or without radiotherapy and chemotherapy. Of the total group of patients (n = 182) TPO-Ab was present in 172, TgAb in 116, and both in 80 patients. Patients were followed for a mean period of 10 years (range 4–20 years). The results were that TgAb disappearance paralleled that of thyroid tissue while TPO-Ab disappearance lagged after complete ablation. At any time during follow-up patients with persistent disease remained positive for TPO-Ab and/or Tg-Ab as compared to patients who were cured (p <0.001). The most important conclusion of this study is that continuing positivity of antithyroid antibodies points to the presence of metastatic disease. |
