Thyroglobulin polymorphisms in Tunisian patients with autoimmune thyroid diseases (AITD)

The thyroglobulin (Tg) gene was reported to be linked and/or associated to autoimmune thyroid diseases (AITD) development in European Caucasian populations. Here, we attempt to replicate this finding and to evaluate the contribution of the Tg gene in the genetic susceptibility of AITD in the Tunisian population. We examined the genomic region (11.5 cM) containing the Tg gene by genotyping seven microsatellite markers and four SNPs located respectively at exon 10 (Ser715Ala), exon 12 (Met1009Val), exon 21 (Ala1483Ala) and exon 33 (Arg1980Trp) in 15 Tunisian multiplex families affected with AITD including Graves' disease (GD) and Hashimoto's thyroiditis (HT) (members: 87; patients: 27 GD and 16 HT). A case-control study was performed by genotyping the Tgms2 intragenic microsatellite marker (intron 27) and four intragenic SNPs on 108 unrelated patients affected with GD and 169 normal controls. Analysis of family data did not show linkage of the thyroglobulin gene with AITD nor did analysis of case-control data show association of Tgms2 or SNPs with GD. In contrast to the European Caucasian population, we failed to detect any contribution of Tg gene in the genetic component of Tunisian AITD.