[Association study on candidate loci of susceptible genes of autoimmune thyroid diseases in a Japanese population].

Autoimmune thyroid diseases(AITD), which include Graves' disease(GD), Hashimoto's thyroiditis(HT), primary hypothyroidism with blocking-type anti-thyrotropin receptor antibody and idiopathic myxedema, are believed to be a multifactorial disease with a significant genetic and environmental component. Several genetic factors associated with AITD susceptibility have been tentatively identified, including the HLA genes and the cytotoxic T lymphocyte associated-4(CTLA-4) gene. More recently, as part of a genome scan, five additional chromosomal locations, i.e., chromosome 5, 8, 9, 15 and X, have recently been reported in a Japanese population. In the present study, in order to confirm evidence obtained by the genome scan, we performed an association study regarding these five candidate loci identified as regions where susceptible genes of AITD exist. Five microsatellite markers, which are located in these loci, were genotyped in a set of 487 unrelated Japanese AITD patients and 218 Japanese controls. Markers located in chromosome 5, 15 and X showed association in AITD patients with significant increase in particular alleles (p < 0.01), while markers in chromosome 8 and 9 did not consistently show significant association. These findings partly support evidence by the previous genome scan that attempted to identify loci of susceptible genes of AITD in a Japanese population; presence of an AITD susceptibility locus at 5q31-33 was suggested. Genotyping using other markers located in these loci would be helpful not only to confirm regions of AITD susceptible genes but also to narrow the regions.