Biomedical subjects

Hitomi Hiratani

Publications and source records attributed to Hitomi Hiratani.

6 recordsLinked to original sources

PubMed2006

No association between complement factor H gene polymorphism and exudative age-related macular degeneration in Japanese.

Age-related macular degeneration (ARMD) is the leading cause of blindness in the elderly population not only Western but also Asian industrial countries. In Caucasian, a polymorphism of the complement factor H gene (CFH), the C allele of rs1061170 (Y402H), was established as the first strong genetic factor for excursively exudative type of ARMD. In this study, we performed an extensive sequencing of the 22 exons in the CFH gene by recruiting 146 exudative ARMD patients and 105 normal controls of Japanese origin and identified 61 polymorphisms. We found that the frequency of the C allele of rs1061170 (Y402H) is much lower (0.04) in Japanese controls than in Caucasians (0.45). No case disease susceptibility to exudative ARMD was noted for rs1061170 (Y402H) (chi (2) = 3.19, P (corr) = 0.423), or other 12 single nucleotide polymorphisms (SNPs) whose frequency is greater than 0.05. When haplotypes were inferred for 13 SNPs (these 12 SNPs with a frequency greater than 0.05 and rs1061170), three haplotypes whose pattern was similar to those in Caucasians were identified but with substantial difference in frequency. Again we failed to identify genetic association between Japanese exudative ARMD and any of the haplotypes including the J1 haplotype which was shown to be susceptible to ARMD in Caucasians (chi (2 )=( )3.92, P (corr) = 0.157). CFH does not appear to be a primary hereditary contributor to ARMD in Japanese. The absence of CFH contribution to ARMD in Japanese may correlate with the findings in ethnic differences of ARMD phenotypes.

Age Factors↗

PubMed2005

Multiple SNPs in intron 7 of thyrotropin receptor are associated with Graves' disease.

Our previous studies using microsatellite markers near or in the TSH receptor (TSHR) gene revealed significant association between autoimmune thyroid disease (AITD) in Japanese patients and TSHR microsatellite alleles. In the present study, we performed a case-control analysis of AITD using single-nucleotide polymorphisms (SNPs) spaced 3-50 kb apart spanning the TSHR gene. We observed significant associations between AITD/Graves' disease (GD)/Hashimoto's thyroiditis and multiple SNPs. Specifically, the SNP JST022302 and several adjacent SNPs in intron 7 of the TSHR gene were significantly associated with GD (P = 0.039-0.0004) but not Hashimoto's thyroiditis. Furthermore, we identified three haplotype blocks around intron 7 by linkage disequilibrium analysis. A single SNP haplotype [AATG(CT)6(TT)AG] in the haplotype block including JST022302 showed significant association with GD in haplotype case-control analysis (P = 0.0058). These findings suggest that alleles of intron 7 of the TSHR gene contribute to GD susceptibility.

Case-Control Studies↗

PubMed2004

SNPs in the promoter of a B cell-specific antisense transcript, SAS-ZFAT, determine susceptibility to autoimmune thyroid disease.

Autoimmune thyroid disease (AITD) is caused by an immune response to self-thyroid antigens and has a significant genetic component. Antisense RNA transcripts have been implicated in gene regulation. Here we have identified a novel zinc-finger gene, designated ZFAT (zinc-finger gene in AITD susceptibility region), as one of the susceptibility genes in 8q23-q24 through an initial association analysis using the probands in the previous linkage analysis and a subsequent association analysis of the samples from a total of 515 affected individuals and 526 controls. The T allele of the single-nucleotide polymorphism (SNP), Ex9b-SNP10 located in the intron 9 of ZFAT, is associated with increased risk for AITD (dominant model: odds ratio = 1.7, P = 0.000091). The Ex9b-SNP10 falls into the 3'-UTR of truncated-ZFAT (TR-ZFAT) and the promoter region of the small antisense transcript of ZFAT (SAS-ZFAT). In peripheral blood lymphocytes, SAS-ZFAT is exclusively expressed in CD19+ B cells and expression levels of SAS-ZFAT and TR-ZFAT seemed to correlate with the Ex9b-SNP10-T-associated ZFAT-allele, inversely and positively, respectively. The Ex9b-SNP10 is critically involved in the regulation of SAS-ZFAT expression in vitro and this expression results in a decreased expression of TR-ZFAT. These results suggested that the SNP-associated ZFAT-allele plays a critical role in B cell function by affecting the expression level of TR-ZFAT through regulating SAS-ZFAT expression and that this novel regulatory mechanism of SNPs might be involved in controlling susceptibility or resistance to human disease.

B-Lymphocytes↗

PubMed2004

Association of the T-cell regulatory gene CTLA4 with Graves' disease and autoimmune thyroid disease in the Japanese.

Autoimmune thyroid disease (AITD) is caused by an immune response to self-thyroid antigen. The cytotoxic T-lymphocyte antigen-4 ( CTLA4) gene, encoding a negative regulator of the T-lymphocyte immune response, had been reported to be associated and/or linked to AITD. Recently, AITD susceptibility in the Caucasians was mapped to the 6.1-kb 3'UTR of the CTLA4 gene, in which the three single-nucleotide polymorphisms (SNPs) CT60, JO31, and JO30 were strongly associated with AITD. In order to determine the association of the CTLA4 gene with AITD in the Japanese, case-control association analysis for the four SNPs of the CTLA4 gene using 380 AITD patients and 266 healthy controls was done. Among the SNPs examined, the SNP JO31 was most significantly associated with AITD in the Japanese, whereas the association of the JO30 with AITD was not observed. The frequency of the disease-susceptible G allele of the JO31 of the Japanese control was higher than that of the Caucasians (67.1% vs 50.2%); however, the G allele of the JO31 was associated with Graves' disease (GD) (67.1% vs 76.3%, P=0.0013) and AITD in the Japanese (67.1% vs 74.2%, P=0.0055). Furthermore, the G allele of the JO31 was associated with the increased risk for GD [ P=0.0051, odds ratio (OR)=1.7] and AITD ( P=0.016, OR=1.5) in a dominant model. These results suggested that the CTLA4 gene is involved in the susceptibility for GD and AITD in the Japanese.

Alleles↗

PubMed2004

Transgenic mice producing major histocompatibility complex class II molecules on thyroid cells do not develop apparent autoimmune thyroid diseases.

The expression of major histocompatibility complex (MHC) class II molecules on thyrocytes has been demonstrated in autoimmune thyroid diseases. However, the role of this aberrant MHC class II in disease development is controversial. In particular, it remains unknown whether MHC class II expression on thyrocytes, which are nonprofessional antigenpresenting cells, plays a role in inducing autoimmune processes. To clarify this issue, we have produced transgenic mice harboring an MHC class II gene ligated to the promoter of the rat TSH receptor. We obtained three lines of transgenic mice, and the expression of MHC class II by the thyrocytes was demonstrated by immunofluorescence staining and flow cytometry. Our examination revealed no obvious abnormalities in thyroid histology or in thyroid autoantibody production in these transgenic mice. Although serum-free T(4) levels were slightly lower than those of their nontransgenic littermates, no transgenic mouse suffered from clinical hypothyroidism or hyperthyroidism. Furthermore, thyroid lymphocytic infiltration was absent, and MHC class II-expressing thyrocytes obtained from transgenic mice failed to stimulate the proliferation of autologous T cells in vitro. Taken together, these results show that transgenic mice with MHC class II molecules on their thyrocytes do not develop apparent autoimmune thyroid diseases, suggesting that aberrant MHC class II expression alone is not sufficient to induce thyroid autoimmunity.

Animals↗

PubMed2003

Association study of autoimmune thyroid disease at 5q23-q33 in Japanese patients.

As part of a genome scan to locate familial Graves' disease (GD) and Hashimoto's thyroiditis (HT) genes, an autoimmune thyroid disease (AITD) susceptibility locus has recently been identified at 5q31-q33 in a Japanese population. We performed an association study using six microsatellite markers located at this locus in a set of 440 unrelated Japanese AITD patients and 218 Japanese controls. We found significant allelic association between AITD and three markers located in 5q23-q33. GD demonstrated significant associations with two of these markers, while HT did not show significant associations with any markers. Further, when patients with GD were stratified according to clinical manifestations, the association was significantly different from the other subgroup of each category. These findings suggest the presence of susceptible genes of AITD, especially distinct subgroups of GD, in or near 5q23-q33.

Alleles↗