¹Laboratoire de Génétique Moléculaire Humaine, Faculté de Médecine de Sfax, 3018 Sfax, Tunisie

²Service de Biochimie. EPS Habib Bourguiba, 3018 Sfax, Tunisie

³Service d'Endocrinologie EPS Hedi Chaker, 3018 Sfax, Tunisie

⁴Dispensaire de Bir EI Hfai, Sidi Bouzid, Tunisie

Correspondence to: Hammadi Ayadi, Laboratoire de Génétique Moléculaire Humaine, Faculté de Médecine, avenue Majida Boulila 3018, Sfax, Tunisie. E-mail: hammadi.ayadi@fmsf.rnu.tn This work was supported by the Délégation Générale de la Recherche Scientifique et Technique (DGRST, TUNISIA).

The autoimmune thyroid diseases (AITDs) including Graves' disease (GD) and Hashimoto's thyroiditis (HT) are inherited as complex traits. We initiated a whole genome linkage study of patients with AITD, in order to identify the susceptibility genes involved in their pathogenesis. We studied 39 patients affected with GD or HT and 68 related controls, who belonged to a large consanguinous family composed of more than 200 members. Linkage analysis was performed using the lod score method under two arbitrary models, one dominant and one recessive. A positive lod score was found for D2S171, assuming a recessive mode of inheritance and 50% penetrance, which suggests the presence of a major AITD susceptibility gene on chromosome 2p21. However, no linkage was found with microsatellite markers spanning the HLA system. This locus localised outside MHC will be of interest for investigation of other autoimmune disorders. Genes and Immunity (2001) 2 , 71-75.

linkage study; autoimmune thyroid disorders; genome screening; susceptibility gene