Lack of association between a polymorphism of human thyrotropin receptor gene and autoimmune thyroid disease.

A polymorphism in codon 52 of the human thyrotropin receptor results in a proline to threonine substitution in the extracellular domain of the receptor, but the association with autoimmune thyroid disease has been uncertain and there is no report the prevalence of this polymorphism in Orientals. To investigate this polymorphism and the association with autoimmune thyroid disease, we studied 113 normal unrelated individuals, 142 autoimmune thyroid disease patients including 112 Graves' disease and 30 Hashimoto's thyroiditis in the Thai population. We screened genomic DNAs of these subjects for the presence of A253 by PCR amplification using a degenerate oligonucleotide primer which produces a Tth111 I restriction site only in the presence of A253. The variant allele was present in 5.3 per cent of normal and 3.5 per cent of autoimmune thyroid disease, 2.7 per cent of Graves' disease and 6.7 per cent of Hashimoto's thyroiditis. The allele distribution in autoimmune thyroid disease patients did not differ significantly from that observed in controls. No association was found between this TSH-R polymorphism and the occurrence of autoimmune thyroid disease.

Simple and sensitive test for thyroid hormone autoantibodies.

We presented a simple and sensitive test for thyroid hormone autoantibodies. The normal range for T4 and T3 autoantibodies in Thai people considering mean +/- 3 S.D. were 1.8-9.4 per cent and 3.1-8.6 per cent, respectively. Although positive low titer of thyroid hormone autoantibodies had almost no interference of thyroid hormone levels, high titer might cause great interference. This method can be used for screening patients who have unexpectably high levels of serum T4, T3 or discrepancy between thyroid hormone levels and clinical findings.