G C A T T A C G G C A T genes Article GPR174 and ITM2A Gene Polymorphisms rs3827440 and rs5912838 on the X chromosome in Korean Children with Autoimmune Thyroid Disease Won Kyoung Cho 1 , Hye-Ri Shin 2, Na Yeong Lee 3, Seul Ki Kim 3 , Moon Bae Ahn 3, In-Cheol Baek 2, Tai-Gyu Kim 2,4,* and Byung-Kyu Suh 3,* 1 Department of Pediatrics, College of Medicine, St. Vincent’s Hospital, The Catholic University of Korea, Seoul 065941, Korea; [email protected] 2 Catholic Hematopoietic Stem Cell Bank, College of Medicine, The Catholic University of Korea, Seoul 065941, Korea; [email protected] (H.-R.S.); [email protected] (I.-C.B.) 3 Department of Pediatrics, College of Medicine, Seoul St. Mary’s Hospital, The Catholic University of Korea, Seoul 065941, Korea; [email protected] (N.Y.L.); [email protected] (S.K.K.); [email protected] (M.B.A.) 4 Department of Microbiology, College of Medicine, The Catholic University of Korea, Seoul 065941, Korea * Correspondence: [email protected] (T.-G.K.); [email protected] (B.-K.S.); Tel.: +82-2-2258-7341 (T.-G.K.); +82-2-2258-6185 (B.-K.S.); Fax: +82-2-594-7355 (T.-G.K.); 82-2-532-6185 (B.-K.S.) Received: 9 June 2020; Accepted: 22 July 2020; Published: 27 July 2020 Abstract: (1) Background: Autoimmune thyroid diseases (AITDs) are female predominant and much attention has been focused on G protein-coupled receptor 174 (GPR174) and integral membrane protein 2A (ITM2A) on the X chromosome as Grave’s disease (GD) susceptible locus. (2) Methods: We genotyped four single nucleotide polymorphisms (SNPs), rs3810712, rs3810711, rs3827440, and rs5912838, of GPR174 and ITM2A in 115 Korean children with AITD (M = 25 and F = 90; GD = 74 (14.7 3.6 years), HD = 41 (13.4 3.2 years); GD-thyroid-associated ophthalmopathy (TAO) = 40, ± ± GD-non-TAO=34) and 204 healthy Korean individuals (M = 104 and F = 100). The data were analyzed by sex-stratified or combined. (3) Results: Three SNPs, rs3810712, rs3810711 and rs3827440, were found to be in perfect linkage disequilibrium (D’ = 1, r2 = 1). In AITD, HD, GD, GD-TAO, and GD-non-TAO patients, rs3827440 TT/T and rs5912838 AA/A were susceptible and rs3827440 CC/C and rs5912838 CC/C were protective genotypes. When analyzed by sex, rs3827440 TT and rs5912838 AA were susceptible and rs3827440 CC and rs5912838 CC were protective genotypes in female AITD, GD, GD-TAO, and GD-non-TAO subjects. In male AITD patients, rs3827440 T and rs5912838 A were susceptible and rs3827440 C and rs5912838 C were protective genotypes. (4) Conclusions: Polymorphisms in GPR174 and ITM2A genes on the X chromosome might be associated with AITD in Korean children. Keywords: autoimmune thyroid disease; gender; GPR174 and ITM2A 1. Introduction Autoimmune thyroid disease (AITD) may occur when genetically susceptible individuals are exposed to environmental triggers such as infection, iodine, or stress [1]. The genetic factor has a major role in AITD etiology and the heritability of Graves’ disease (GD) has been reported to be 79% [2]. AITD encompasses GD and Hashimoto’s thyroiditis (HD) [3]. HD seems to involve a CD4 Th1 response. The effects of antibodies and effector T cells specific for thyroid antigens lead to the progressive destruction of normal thyroid tissue. The autoimmune response in GD is biased towards a CD4 Th2 Genes 2020, 11, 0858; doi:10.3390/genes11080858 www.mdpi.com/journal/genes Genes 2020, 11, 0858 2 of 15 response and is focused on antibody production. The production of anti-thyroid Stimulating Hormone (TSH) receptor antibodies promotes chronic overproduction of thyroid hormone [3]. However, the fact that GD and HD are commonly observed in the same family tree reflects a similar genetic basis for these diseases [4,5]. In early onset autoimmune disease, genetic susceptibility might be greater concern than in late onset cases [6]. We have reported an increase in allele frequencies of HLA-B*46, -DRB1*08, and -Cw*01 [7]. The statistical significance in our previous study was much higher than observed in other studies conducted on Korean adults [8], which might suggest that early-onset AITD is more influenced by genetic factors than late-onset AITD. The female predominance in autoimmune disease has long been recognized and the most striking sex differences in prevalence are observed in AITD (>80% women) [9,10]. However, the biology of sexual dimorphismGenes 2020 in, 11, AITD x FOR PEERis REVIEW not clearly understood. Recently, a great2 dealof 18 of attention has focused on sexualprogressive dimorphism destruction in of thenormal immune thyroid tissue. response. The autoimmune Sex response dimorphisms in GD is biased towards in immune response a CD4 Th2 response and is focused on antibody production. The production of anti-thyroid appear to be partiallyStimulating associated Hormone with(TSH) receptor direct antibodies genetic promotes differences chronic overproduction such as X of chromosome thyroid and linked genes, and sex hormonehormone and [3]. However, sex-specific the fact that regulation GD and HD ofare commonly immune-related observed in the genes same family [11 ].tree The X chromosome reflects a similar genetic basis for these diseases [4,5]. In early onset autoimmune disease, genetic contains approximatelysusceptibility 1000 might genes, be greater including concern than in many late onset immune-related cases [6]. We have reported genes an increase that in encode receptors allele frequencies of HLA-B*46, -DRB1*08, and -Cw*01 [7]. The statistical significance in our previous and associated proteins,study was immunemuch higher than response-related observed in other studiesproteins conducted on andKorean transcriptionaladults [8], which might and translational regulator [12]. Somesuggest genes that locatedearly-onset AITD on the is more X influenc chromosomeed by genetic mayfactors than play late-onset an important AITD. role in susceptibility The female predominance in autoimmune disease has long been recognized and the most to GD [13]. Furthermore,striking sex X chromosomedifferences in prevalence inactivation are observed in and AITD skewing (>80% women) might [9,10]. beHowever, important the contributors to biology of sexual dimorphism in AITD is not clearly understood. Recently, a great deal of attention the increased risk forhas AITDfocused on in sexual females dimorphism [14 –in16 the]. immune response. Sex dimorphisms in immune response Previous studiesappear found to be partially associations associated with with direct genesgenetic differences on the such X as chromosome X chromosome and inlinked patients with AITD. genes, and sex hormone and sex-specific regulation of immune-related genes [11]. The X chromosome Associations of AITDcontains have approximately been 1000 reported genes, including with many polymorphisms immune-related genes that of encode FOXP3 receptors in and Caucasian [17] and Japanese [18], TLR7associated in a Chineseproteins, immune Cantonese response-related population proteins and [19 transcriptional] and IRAK1 and translational in Chinese [20]. We also regulator [12]. Some genes located on the X chromosome may play an important role in susceptibility reported that polymorphismsto GD [13]. Furthermore, of IRAK1 X chromosome gene inactivati on Xon chromosomeand skewing might be is important associated contributors with HD in Korean to the increased risk for AITD in females [14–16]. children [21]. Recently,Previous the studies rs3827440 found associations and rs5912838 with genes on the single X chromosome nucleotide in patients polymorphisms with AITD. (SNPs) in G protein-coupledAssociations receptor of 174AITD (haveGPR174 been reported) and with integral polymorphisms membrane of FOXP3 in Caucasian protein [17] 2A and (ITM2A) on the X Japanese [18], TLR7 in a Chinese Cantonese population [19] and IRAK1 in Chinese [20]. We also chromosome werereported suggested that polymorphisms to be GD-susceptible of IRAK1 gene on X chromosome loci after is theassociated major with histocompatibilityHD in Korean complex region [13,22]. However,children [21]. to Recently, the bestthe rs3827440 of our and rs5912838 knowledge, single nucleotide there polymorphisms have been (SNPs) no in reportsG on possible protein-coupled receptor 174 (GPR174) and integral membrane protein 2A (ITM2A) on the X associations of GPR174chromosomeand wereITM2A suggestedpolymorphisms to be GD-susceptible lociwith after the AITD major histocompatibility in Korean complex children. In this study, region [13,22]. However, to the best of our knowledge, there have been no reports on possible we investigated theassociations role of ofGPR174 GPR174 and ITM2Aand polymorphismsITM2A polymorphisms with AITD in Korean children. (rs3810712, In this study, rs3810711, we rs3827440, rs5912838) with AITDinvestigated in Korean the rolechildren of GPR174 and (Figure ITM2A1 polymorphismsA). (rs3810712, rs3810711, rs3827440, rs5912838) with AITD in Korean children (Figure 1A). (A) (B) Figure 1. (A), G protein-coupled receptor 174 (GPR174) and integral membrane protein 2A (ITM2A) variants region have been reported from GRCh37.p13 (hg19). rs3810712, 5 prime untranslated region (‘UTR) variant, C>G,T; rs3810711, 50UTR variant, T>C,G; rs3827440, missense variant, T>A,C,G; rs5912838, 30UTR variant, A>C,G; (B), block and frequency of linkage disequilibrium (LD) of selected four single nucleotide polymorphisms (SNPs) in GPR174. Boxes are colored deep red if the D’ values are high, which means LD is more strong. Especially, rs3810712, rs3810711 and rs3827440 were found to be in perfect linkage disequilibrium (D’ = 1, r2 = 1). Genes 2020, 11, 0858 3 of 15 2. Materials and Methods 2.1. Subjects The present study is a noninterventional registry study. There were 206 patients diagnosed with AITD who agreed to participate in this study between March 2009 and August 2019 in the pediatric endocrine clinic at Seoul St. Mary’s and St. Vincent’s Hospitals. Among these 206, subjects who had blood sample insufficient for genetic study (n = 91) were excluded. Ultimately, our study included 115 patients (90 females and 25 males) diagnosed with AITD (41 HD and 74 GD cases).