Circulation Journal REVIEW Official Journal of the Japanese Circulation Society http://www.j-circ.or.jp Genetics of Kawasaki Disease – What We Know and Don’t Know – Yoshihiro Onouchi MD, PhD

Kawasaki disease (KD) is a leading cause of acquired heart disease in children in developed countries. Although it has been thought that symptoms of KD are related to hyperactivation of the immune system triggered by infection with some microorganisms, the etiological agent still remains unknown. In this situation, genetic factors underlying the disease pathogenesis, which have been suggested by epidemiological findings, are expected to be clues to the enigma. Recently, susceptibility genes for KD have been identified in succession by studies with a genome-wide approach. Recent advances in genetic studies for KD will be presented. (Circ J 2012; 76: 1581 – 1586)

Key Words: Genetics; Kawasaki disease; Single nucleotide polymorphisms

awasaki disease (KD) was firstly described by Dr lated to a lifestyle common in East Asian populations. How- Tomisaku Kawasaki, a Japanese pediatrician in 1967.1 ever, epidemiological data from Hawaii strongly suggest that K Because in many cases the disease was self-limiting, the differences in incidence of KD among ethnicities is related initially it was thought to be benign. However, cases of sudden to genetic factors. Holmans et al reported that the average an- death of KD patients with coronary artery aneurysms and throm- nual incidence rate of KD among Japanese Americans in Hawaii bo-embolic occlusion has made KD widely known. It is known from 1996 to 2006 was 210.5, which is almost the same as that that, if untreated, 20–25% of KD patients will develop coro- in mainland Japan.9 On the other hand, the incidence among nary artery lesions (CAL) represented by aneurysms and dila- white children in Hawaii was 13.7, which was comparable with tations.2,3 Although the incidence of CAL has been lowered to that in the US mainland (12.0).10 less than 5% after the introduction of intravenous immuno- High relative risk of KD among the family members of a globulin therapy (IVIG), KD is still a leading cause of acquired KD patient is also known. Siblings of a KD patient are at 10– heart disease in children in developed countries. Because 10– 30-fold higher risk of KD compared with the general popula- 15% of patients require additional IVIG because of resistance,3 tion.11 Investigation of the parents of a KD patient revealed development of treatment strategies addressing the root cause that the percentage of having a positive past history of KD was of the disease is expected. KD has been considered to be a dis- twice as high in parents of a KD patient than in the general ease caused by some microbial infection of genetically sus- population.12 Also, the odds of having sibling cases were sig- ceptible individuals. However, although much effort has been nificantly increased among patients whose parents also had KD made, the etiological agent of KD remains unknown. Therefore, (odds ratio [OR], 6.94). Patients with parental KD were more genetic studies of KD are conducted not only to clarify the ge- likely to experience recurrent KD (OR 2.88).13 netic background but also in the hope of providing clues about Therefore, it is highly probable that interindividual variabil- its etiology. ity in susceptibility to KD and different prevalence of KD among races or ethnicities are related to genetic components. Epidemiologic Data Suggesting Genetic Component of KD Genome-Wide Linkage Study of KD Today, more than 12,000 individuals will be newly diagnosed In an attempt to identify the association of genetic polymor- as KD in Japan in 1 year and the annual incidence rate was 222.9 phisms with susceptibility to KD or with disease severity, many per 100,000 children aged 0–4 years in 2010.4 The annual in- candidate genes related to innate and acquired immune func- cidence in Japan is more than 10-fold higher than in the US tion or to vascular remodeling have been studied.14–17 How- (20.8)5 and UK (8.4).6 It is higher in East Asian countries, and ever, most of these earlier studies failed to identify a definitive Korea (113.1)7 and Taiwan (69.0)8 have the second and the association that can be universally confirmed, emphasizing the third highest annual incidence of KD. These data give the im- difficulty of setting candidate genes for diseases of which the pression that KD is a type of endemic disease or a disease re- pathogenesis is largely unknown.

Received May 9, 2012; revised manuscript received May 24, 2012; accepted May 27, 2012; released online June 7, 2012 Department of Public Health, Chiba University Graduate School of Medicine, Chiba and Laboratory for Cardiovascular Disease, Center for Genomic Medicine, Riken, Yokohama, Japan Mailing address: Yoshihiro Onouchi, MD, PhD, Department of Public Health, Chiba University Graduate School of Medicine, 1-8-1 Inohana, Chuo-ku, Chiba 260-8670, Japan. E-mail: [email protected] ISSN-1346-9843 doi: 10.1253/circj.CJ-12-0568 All rights are reserved to the Japanese Circulation Society. For permissions, please e-mail: [email protected]

Circulation Journal Vol.76, July 2012 1582 ONOUCHI Y

Table 1. Genome-Wide Association Studies for KD GWAS Follow-up strategy Reference Samples Case-control study Family-based No. of SNPs Population KD* Control KD* Control study 26 223,922 European 119 135 – - 583 families 33 641,760 Korean 186 (63) 600 266 (88) 600 – 37 723,638 Taiwanese 250 446 208 366 – 42 494,236 European 405 6,252 1,028** 1,512** 740 families 45 473,803 Japanese 428 3,379 754 947 – 46 716,935 Taiwanese 622 1,107 261 550 – *Numbers in brackets indicate KD patients with coronary artery lesion. **Sum of 3 Asian case-control panels. KD, Kawasaki disease; SNP, single nucleotide polymorphism.

In contrast to the candidate gene approach, whole genome analysis of these 3 studies afforded convincing evidence that scanning without hypothesis has the advantage of identifying the SNP also underlies the genetic background of KD in the disease genes even if the functions of the genes are not associ- Taiwanese population.27 As for CASP3, there has been only 1 ated with previous knowledge about the disease’s pathophysi- replication study reporting a marginal association of the same ology. We carried out the first genome-wide study of KD. A allele of rs113420705 with KD in a Taiwanese population.28 linkage study of an affected sibpair method identified 10 chro- mosomal loci with lod (logarithm of odds) scores larger than 1.0.18 From these candidate loci, several single nucleotide Genome-Wide Association Studies of KD polymorphisms (SNPs) associated with susceptibility to KD or Identification of susceptibility genes of complex diseases has risk for CAL have been identified. Using a positional candi- been accelerated since the genome-wide association study date gene approach, a SNP within the CD40 ligand (CD40L) (GWAS) was introduced. Until now, 6 GWAS for KD suscep- gene, which was polymorphic in Japanese, but not in Euro- tibility genes have been published (Table 1). The first GWAS Americans, and associated with CAL in male KD patients, for KD was conducted in a European population.29 Burgner et was identified.19 CD40L was located near the linkage peak on al conducted a GWAS with Dutch KD cases and controls and Xq26 in the sibpair study. CD40L, which is ex- followed up association signals with a family-based associa- pressed on the surface of CD4+ T-cells and platelets, engages tion study of KD families from Australia, USA and the UK. In with CD40, the receptor for CD40L expressed on the surface that study, SNPs within N-acetylated α-acidic dipeptidase-like of antigen-presenting cells (APCs) or vascular endothelial 2 (NAALADL2) and zinc finger homeobox 3 ZFHX3( ) genes cells and transduce signals related to cell activation or devel- showed the most significant association in the combined data opment.20 Elevated expression of CD40L during acute-phase analyses. NAALADL2 is located on chromosome 3q26.31 and KD and significantly higher expression in KD patients with rs1463525 located in intron 3 of NAALADL2 was associated CAL have been reported.21 However, unfortunately, the trend with KD (P=1.13×10−6). Previously, NAALADL2 drew atten- of association seen in Japanese KD patients was not replicated tion as a candidate gene for Cornelia de Lange syndrome in a subsequent study in the Taiwanese population.22 (CdLS), a developmental disorder, because the gene was dis- By linkage disequilibrium (LD) mapping performed on the rupted by a t(3; 17)(q26.3; q23.1) translocation in a patient candidate region of chromosome 19q13.2, we identified a SNP with CdLS. However, no point mutation has been identified in within the inositol 1,4,5-trisphosphate (IP3) kinase-C (ITPKC) subsequent mutation screening of 80 CdLS patients.30 Although gene, which confers both susceptibility to KD and risk for the function of NAALADL2 protein is poorly understood, the CAL.23 ITPKC is a kinase of IP3, a second messenger mole- result of transcriptome analyses performed by the same group29 cule involved in the Ca2+/NFAT pathway. The risk allele of showed a reduction of mRNA expression of NAALADL2 in the responsible SNP (rs28493229, C allele) alters the splicing blood cells in the acute phase of KD compared with that in the efficiency ofITPKC intron 1 and then decreases the amount of convalescent phase, indicating a possible involvement of the mature ITPKC mRNA. The results of overexpression and knock- protein in immune homeostasis. ZFHX3, also known as AT down experiments using a T-lineage cell line indicate a nega- motif binding factor 1 (ATBF1), is a transcription factor pro- tive regulatory role of ITPKC in the Ca2+/NFAT pathway. A tein containing multiple homeodomains and multiple zinc fin- SNP within the caspase-3 (CASP3) gene located on 4q34-35 ger motifs. ZFHX3 protein is expressed in the heart, liver, lung, associated with KD susceptibility was identified by a positional kidney pituitary gland and brain. ZFHX3 was reported to be a candidate gene study and also reported from our group.24 CASP3 tumor suppressor and frequent somatic mutations of ZFHX3 is an executioner caspase deeply related to apoptosis of im- have been observed in cells.31 The GWAS per- mune cells. The G to A transition within exon 1 of CASP3 formed in the European population revealed that SNPs within (rs113420705) reduces the binding of the nuclear factor of intron 1 of ZFHX3 (rs2106261 and rs7193343) were signifi- activated T cells (NFAT) to the DNA surrounding the SNP cantly associated with atrial fibrillation (AF)32,33 and the as- and then decreases the transcription of CASP3 mRNA. Asso- sociation of rs2106261 with AF was replicated in the Chinese ciations of both SNPs were validated in Euro-American triads Han population.34 In the GWAS for KD, rs7193343 was as- of KD patients and their biological parents in the original re- sociated, but, contrary to the promoting effect on AF risk, the ports.23,24 Three different groups from Taiwan independently minor allele had a protective effect on the risk for KD (OR tested the reproducibility of the association of rs28493229, the 0.64, P=2.37×10−6). The reason for the opposite direction of functional SNP of ITPKC.25–27 Although not always significant, association may be clarified after understanding the downstream all 3 groups reported the same trend of association and a meta- molecules of ZFHX3, which should play different roles in dif-

Circulation Journal Vol.76, July 2012 Genetics of Kawasaki Disease 1583 ferent cells and developmental stages in the pathogenesis of of a sequence similarity within the gene cluster that disturbs each disease. genotyping, there is an unexplored genomic region adjacent to Kim et al reported results for a GWAS of KD in a Korean FCGR2A, and determination of the true responsible variant of population.35 Association studies with KD cases and controls, the awaits analysis of the region. as well as that with KD cases with CAL and controls, were car- In 2012, Japanese and Taiwanese groups independently re- ried out. A SNP within the disabled homolog 1 (Drosophila) ported GWAS results.46,47 In both studies, significant associa- (DAB1) gene locus in chromosome 1 showed the most signifi- tions were observed in the FAM167A-BLK region on chromo- cant association with KD susceptibility (rs527409, P=1.46× some 8p23–p22. The association peak in this locus was located 10−6). The function of this protein in inflammatory processes at the intergenic region between BLK (B lymphoid kinase), a or vascular homeostasis is unknown. In an association study src family tyrosine kinase expressed mainly in B cells and in- for risk for CAL, rs7604693 located within intron 1 of the pel- volved in B-cell receptor signal transduction by phosphorylat- lino homolog 1 (Drosophila) (PELI1) gene in chromosome 2 ing the ITAM region of Igα and Igβ molecules and FAM167A, showed a suggestive trend of association (P=2.00×10−6). PELI a functionally uncharacterized gene. BLK has also been re- proteins are RING E3 ubiquitin ligases related to regulation of ported to be responsible for phosphorylation of the immuno- signaling from Toll like receptors and IL-1 receptor.36 PELI1 receptor tyrosine-based inhibitory motif of the FCGR2B mol- has another function as a negative regulator of T cell receptor ecule.48 Pancreatic β-cells also express BLK and a mutation of signaling. Peli1-deficient mice were prone to autoimmunity BLK leads β-cell dysfunction causing autosomal dominant ma- and T cells from the mice were hyper-responsive to stimula- turity-onset diabetes of the young (MODY11).49 tion with anti-CD3 and anti-CD28.37 The negative regulatory SNPs around CD40 located on chromosome 20q12–q13.2 effect of Peli1 on T cell activity is mediated through ubiqui- were also associated with KD at genome-wide significance in tination and degradation of c-Rel. both Japanese and Taiwanese GWAS.46,47 The most significant Tsai et al reported the result of a GWAS of KD in a Taiwanese association within the CD40 region in the Taiwanese popula- population.38 Among several loci showing association with P tion was seen for rs1569723, which is 4.8 kb upstream of values smaller than 1.0×10−4 in the joint analysis of GWAS the CD40 transcription start site and is tightly linked with and follow-up study, the authors pointed out 3 loci as plausible rs1883832, located just 1 base upstream of the first nucleotide candidates. The first locus was near the coatmer protein com- of the initiation codon (ATG) of the gene and alters the protein plex beta-2 subunit (COPB2) gene located on chromosome translation efficiency by a C to T transition.50 On the other hand, 3q23. The Golgi coatomer complex constitutes the coating of rs4813003, located 4.9kb downstream of CD40, showed the non-clathrin-coated vesicles and is essential in Golgi budding most significant association with KD in this locus in Japanese and vesucular trafficking. COPB2 is one of the 7 protein sub- subjects.46 A correlation between genotypes at rs4813003 and units of which the Golgi coatomer complex consists. The au- the ratio of alternatively spliced CD40 transcripts generating thors speculated that COPB2 plays a role in the regulation of protein lacking the transmembrane domain as a consequence T cell receptor signaling. In 5q15 region, 2 SNPs within the of exon 6 skipping has been shown. Considering that the risk second intron of the endoplasmic reticulum aminopeptidase 1 alleles at rs1883882 and rs4813003 are related to enhancement (ERAP1) gene were associated with KD. ERAP1 is a member of CD40 function through increased translation efficiency and of the M1 family of zinc metallopeptidases known to play roles a reduction of functionally null isoform, respectively, and that in peptide trimming for HLA class I presentation and in cleav- expression of CD40L is upregulated in the acute phase of ing cell surface receptors for cytokines such as TNF, IL1 and KD,21 it is likely that CD40L–CD40 signaling plays a facilitat- IL6. It should be noted that SNPs in ERAP1 have been associ- ing role in disease progression and could be a novel target of ated with ankylosing spondylitis39,40 and psoriasis.41,42 Multi- molecular therapies. ple SNPs in the immunoglobulin heavy chain variable region Associations of HLA alleles with susceptibility to various (IGHV) gene cluster on 14q23.33, which are in high LD, also diseases, especially of an autoimmune nature, is widely known. showed association with KD (P=1.28×10−5–6.77×10−6). From As for KD, whether or not HLA is involved in the pathogen- a statistical point of view these loci are still strong candidates esis has long been controversial, because no large association and require confirmation of associations in independent co- study has been conducted until recently and the positive results horts. in candidate gene studies with relatively small-sized samples Association of a SNP within the Fc gamma receptor gene have not been validated in subsequent replication studies.14 In cluster on chromosome 1 was identified through a GWAS with a recent GWAS,46 a significant association of the SNPs in HLA a case-control set with European descent and follow-up by a class II region with KD was identified. The association peaked family-based study of mixed ancestry and a series of case- at the intergenic region between HLA-DQB2 and HLA-DOB control studies of 3 different Asian populations.43 The stron- (rs2857151, P=4.6×10−11). A suggestive association signal was gest association in the locus was seen on rs1801274 on the Fc also observed near the nuclear factor of kappa light polypep- fragment of IgG, low affinity IIa, receptor FCGR2A)( gene and tide gene enhancer in B-cell inhibitor-like 1 (NFKBIL1) and the overall P value was 7.35×10–11. rs1801274 was the first lymphotoxin-α (LTA) genes in HLA class III region (rs2516390, susceptibility SNP for KD identified with genome-wide sig- P=6.8×10−8). However, no significant association of the SNPs nificant association (P<5.0×10−8) in a GWAS. FCGR2A is ex- in the 6p21.3 region has been documented in other GWAS pressed on the surface of dendritic cells, monocytes, macro- reports. phages and neutrophils and transduces activating signals into the cells via an immunoreceptor tyrosine-based activation motif Overlapping of Genetic Factors With (ITAM) in its cytoplasmic domain when ligated with immune complexes.44 The A to G substitution of the SNP alters the Other Disorders translation of the 131st amino acid from histidine (H) to argi- Until recently, pathogenetic relatedness between KD and other nine (R). Compared with the R131 isoform, H131 has higher diseases has not been clearly demonstrated. However, a series binding affinity to the IgG2 subclass,45 which is responsible for of GWAS findings are evidence of overlapping of genetic com- antibodies against bacterial polysaccharides. However, because ponents with other inflammatory disorders. rs1801274 [A al-

Circulation Journal Vol.76, July 2012 1584 ONOUCHI Y

Table 2. Susceptibility Genes for KD Identified With Association at Genome-Wide Significance (P<5.0×10–8) Original Replication studies Gene Locus Methods reports Positive Negative FCGR2A* 1q23 GWAS 42 45 – Linkage analysis – positional CASP3 4q34–35 21 25** – candidate gene study HLA* 6p21.3 GWAS 45 – – BLK* 8p23–p22 GWAS 45, 46 – – Linkage analysis – linkage ITPKC 19q13.2 20 23, 42 22, 24 disequilibrium mapping CD40* 20q12-q13.2 GWAS 45, 46 – – *Functional SNPs have not been specified. **P=0.052. KD, Kawasaki disease; GWAS, genome-wide association study; SNP, single nucleotide polymorphism.

Table 3. Comparison of Risk Allele Frequencies of Susceptibility SNPs Gene FCGR2A CASP3 HLA BLK ITPKC CD40 Population rs1801274 rs113420705 rs2857151 rs2254546 rs28493229 rs4813003 SNP* A/G G/A A/G A/G G/C C/T Japanese 0.7945 0.3721 0.7545 0.7145 0.1620 0.6745 Taiwanese 0.6342 0.3125 0.73** 0.81** 0.05445 0.68** European 0.5442 0.73† 0.58† 0.88† 0.1545 0.87† *Risk alleles are underlined. **RAF in the HapMap Han Chinese in Beijing (CHB) population. †RAF in the HapMap CEU, (CEPH (Utah residents with ancestry from northern and western Europe)) population. SNP, single nucleotide polymorphism.

BLK region have been associated with several autoimmune diseases such as rheumatoid arthritis,54–58 systemic lupus ery- thematosus,52,59–63 and systemic sclerosis.64–66 The functional SNP of CD40 (rs1883832) has been associated with Grave’s disease in candidate gene studies.67–69 In recent GWAS, SNPs at the 5’ end of CD40 and in high linkage disequilibrium with rs1883832 showed significant association with rheumatoid ar- thritis,70,71 systemic lupus erythematosus72 and multiple scle- rosis.73 On the other hand, there are currently no reports de- scribing a positive association of functional SNPs of either ITPKC or CASP3 with diseases other than KD. These obser- vations might be telling us that KD is sharing part of the gene networks that play important roles in its pathogenesis with other inflammatory disorders.

Have Our Questions Been Answered? One strong interest is whether the findings to date explain the higher incidence of KD in East Asian populations. Risk allele frequencies of 6 SNPs, including 5 SNPs definitively associated Figure. Receiver-operating characteristic (ROC) curve for with KD in the Japanese samples (rs28493229, rs113420705, predictive model of Kawasaki disease with 6 single nucleotide rs2254546, rs2857151 and rs4813003) and rs1801274 (Table 2), polymorphisms (SNPs) (rs28493229, rs113420705, rs2254546, were compared among Japanese, Taiwanese and European rs2857151, rs4813003 and rs1801274). After determining the best inheritance model to explain the involvement of each populations. However, contrary to expectations, those in the SNP in the training samples (428 KD and 3,379 controls) by Europeans are comparable to or, for some SNPs, higher than logistic regression analyses, a multiple logistic regression those in Asians (Table 3). model of 6 SNPs was developed. The model was evaluated Clarification of the microorganism triggering the symptoms in the test samples (754 KD and 947 controls). (ROC curve of KD is essential to both a complete understanding of the drawn using Epi package in R 2.13 statistical environment.) pathogenesis and developing more effective therapeutic mea- sures and preventive strategies. However, unfortunately previ- ous microbiological analyses of clinical specimens obtained lele] of FCGR2A conferring susceptibility to KD has been as- from acute-phase KD patients have not succeeded in specify- sociated with increased risk for ulcerative colitis51 and decreased ing the pathogen. One theory is that the causal agents have risk for systemic lupus erythematosus.52 A SNP located in the been significantly reduced or already disappeared from the 5’ upstream region of FCGR2A (rs10800309) has also been patient’s body at the time of diagnosis. If so, accurate genetic associated with ulcerative colitis.53 Variations in the FAM167A- prediction of infants who will be affected with KD will be ben-

Circulation Journal Vol.76, July 2012 Genetics of Kawasaki Disease 1585 eficial because it will increase the researchers’ opportunities tory pathogens. Pediatr Infect Dis J 2009; 28: 21 – 24. to witness the onset of KD and to take specimens that should 7. Park YW, Han JW, Hong YM, Ma JS, Cha SH, Kwon TC, et al. contain higher amount of the agent(s) earlier in the illness. Epidemiological features of Kawasaki disease in Korea, 2006–2008. Pediatr Int 2011; 53: 36 – 39. Creation of a multiple logistic model to predict the onset of 8. Huang WC, Huang LM, Chang IS, Chang LY, Chiang BL, Chen PJ, KD using genotype information at the 6 SNPs has been at- et al. Epidemiologic features of Kawasaki disease in Taiwan, 2003– tempted. However, none of the area under the receiver-operat- 2006. Pediatrics 2009; 123: e401 – e405. ing characteristic curve (0.64), sensitivity (55.6%), specificity 9. Holman RC, Christensen KY, Belay ED, Steiner CA, Effler PV, Miyamura J, et al. Racial/ethnic differences in the incidence of Kawasaki (65.6%), positive predictive value (56.7%) and negative syndrome among children in Hawaii. Hawaii Med J 2010; 69: 194 – predictive value (64.5%) indicated a high predictive value 197. (Figure). 10. Holman RC, Belay ED, Christensen KY, Folkema AM, Steiner CA, Schonberger LB. Hospitalizations for Kawasaki syndrome among children in the United States, 1997–2007. Pediatr Infect Dis J 2010; Future Direction 29: 483 – 488. 11. Fujita Y, Nakamura Y, Sakata K, Hara N, Kobayashi M, Nagai M, GWAS might have succeeded in identifying part of the ge- et al. Kawasaki disease in families. Pediatrics 1989; 84: 666 – 669. netic background of KD. Because the numbers of samples ana- 12. Uehara R, Yashiro M, Nakamura Y, Yanagawa H. Kawasaki disease in parents and children. Acta Paediatr 2003; 92: 694 – 697. lyzed in the studies were not large, there must be many ge- 13. Uehara R, Yashiro M, Nakamura Y, Yanagawa H. Clinical features netic factors that have been overlooked in the GWAS by those of patients with Kawasaki disease whose parents had the same dis- studies’ lack of power. Oligo- or monomorphic variations in ease. Arch Pediatr Adolesc Med 2004; 158: 1166 – 1169. the European populations and excluded from the GWAS plat- 14. Onouchi Y. Molecular genetics of Kawasaki disease. Pediatr Res forms have not been investigated. Meta-analyses of GWAS 2009; 65: 46R – 54R. 15. Weng KP, Hsieh KS, Ho TY, Huang SH, Lai CR, Chiu YT, et al. data from different ethnic groups may partly overcome the IL-1B polymorphism in association with initial intravenous immu- weakness in statistical power. GWAS with many more KD noglobulin treatment failure in Taiwanese children with Kawasaki cases and controls using ethnically optimized genotyping plat- disease. Circ J 2010; 74: 544 – 551. forms show more promise. Exome sequencing study will be 16. Weng KP, Hsieh KS, Hwang YT, Huang SH, Lai TJ, Yuh YS, et al. IL-10 polymorphisms are associated with coronary artery lesions in applied to KD cases of some extreme subphenotypes, such as acute stage of Kawasaki disease. Circ J 2010; 74: 983 – 989. development of giant aneurysms or frequent recurrence of 17. Weng KP, Ho TY, Chiao YH, Cheng JT, Hsieh KS, Huang SH, et al. KD, and will clarify the contribution of rarer variants or muta- Cytokine genetic polymorphisms and susceptibility to Kawasaki dis- tions of known or novel susceptibility genes. Accumulation of ease in Taiwanese children. Circ J 2010; 74: 2726 – 2733. 18. Onouchi Y, Tamari M, Takahashi A, Tsunoda T, Yashiro M, Nakamura susceptibility genes will facilitate in silico pathway analyses. Y, et al. A genomewide linkage analysis of Kawasaki disease: Evi- Analyses of genetically modified animals with identified sus- dence for linkage to chromosome 12. J Hum Genet 2007; 52: 179 – ceptibility genes might also provide valuable insights to the 190. pathophysiology and hopefully identify novel treatment tar- 19. Onouchi Y, Onoue S, Tamari M, Wakui K, Fukushima Y, Yashiro M, et al. CD40 ligand gene and Kawasaki disease. Eur J Hum Genet gets. 2004; 12: 1062 – 1068. 20. van Kooten C, Banchereau J. CD40-CD40 ligand. J Leukoc Biol 2000; 67: 2 – 17. Summary 21. Wang CL, Wu YT, Liu CA, Lin MW, Lee CJ, Huang LT, et al. Ex- By virtue of the completion of the Project pression of CD40 ligand on CD4+ T-cells and platelets correlated to the coronary artery lesion and disease progress in Kawasaki disease. and information provided by the International HapMap Proj- Pediatrics 2003; 111: E140 – E147. ect, as well as remarkable advances in genotyping technology, 22. Huang FY, Chang TY, Chen MR, Chiu NC, Chi H, Lee HC, et al. we have eventually started to learn about assured susceptibil- Genetic polymorphisms in the CD40 ligand gene and Kawasaki dis- ity genes for KD after more than 40 years of research into the ease. J Clin Immunol 2008; 28: 405 – 410. 23. Onouchi Y, Gunji T, Burns JC, Shimizu C, Newburger JW, Yashiro M, disease. However, these might be mere pieces of a puzzle et al. ITPKC functional polymorphism associated with Kawasaki without solution. In parallel with trying to work out the puzzle, disease susceptibility and formation of coronary artery aneurysms. we have to keep searching for the missing pieces. Nat Genet 2008; 40: 35 – 42. 24. Onouchi Y, Ozaki K, Burns JC, Shimizu C, Hamada H, Honda T, et al. Common variants in CASP3 confer susceptibility to Kawasaki dis- Acknowledgment ease. Hum Mol Genet 2010; 19: 2898 – 2906. The author declares no competing financial interests. 25. Chi H, Huang FY, Chen MR, Chiu NC, Lee HC, Lin SP, et al. ITPKC gene SNP rs28493229 and Kawasaki disease in Taiwanese children. Hum Mol Genet 2010; 19: 1147 – 1151. References 26. Lin MT, Wang JK, Yeh JI, Sun LC, Chen PL, Wu JF, et al. Clinical 1. Kawasaki T. Acute febrile mucocutaneous syndrome with lymphoid implication of the C allele of the ITPKC gene SNP rs28493229 in involvement with specific desquamation of the fingers and toes in Kawasaki Disease: Association with disease susceptibility and BCG children. Arerugi 1967; 16: 178 – 222 (in Japanese). scar reactivation. Pediatr Infect Dis J 2011; 30: 148 – 152. 2. Kato H, Koike S, Yamamoto M, Ito Y, Yano E. Coronary aneurysms 27. Kuo HC, Yang KD, Juo SH, Liang CD, Chen WC, Wang YS, et al. in infants and young children with acute febrile mucocutaneous ITPKC single nucleotide polymorphism associated with the Kawasaki lymph node syndrome. J Pediatr 1975; 86: 892 – 898. disease in a Taiwanese population. PLoS One 2011; 6: e17370. 3. JCS Joint Working Group. Guidelines for diagnosis and management 28. Kuo HC, Yu HR, Juo SH, Yang KD, Wang YS, Liang CD, et al. of cardiovascular sequelae in Kawasaki disease (JCS 2008): Digest CASP3 gene single-nucleotide polymorphism (rs72689236) and version. Circ J 2010; 74: 1989 – 2020. Kawasaki disease in Taiwanese children. J Hum Genet 2011; 56: 4. Nakamura Y, Yashiro M, Uehara R, Sadakane A, Tsuboi S, Aoyama 161 – 165. Y, et al. Epidemiologic features of Kawasaki Disease in Japan: Re- 29. Burgner D, Davila S, Breunis WB, Ng SB, Li Y, Bonnard C, et al. A sults of the 2009–2010 nationwide survey. J Epidemiol 2012; 3: genome-wide association study identifies novel and functionally 216 – 221. related susceptibility loci for Kawasaki disease. PLoS Genet 2009; 5. Holman RC, Belay ED, Christensen KY, Folkema AM, Steiner CA, 5: e1000319. Schonberger LB. Hospitalizations for Kawasaki syndrome among 30. Tonkin ET, Smith M, Eichhorn P, Jones S, Imamwerdi B, Lindsay S, children in the United States, 1997–2007. Pediatr Infect Dis J 2010; et al. A giant novel gene undergoing extensive alternative splicing is 29: 483 – 488. severed by a Cornelia de Lange-associated translocation breakpoint 6. Harnden A, Mayon-White R, Perera R, Yeates D, Goldacre M, Burgner at 3q26.3. Hum Genet 2004; 115: 139 – 148. D. Kawasaki disease in England: Ethnicity, deprivation, and respira- 31. Sun X, Frierson HF, Chen C, Li C, Ran Q, Otto KB, et al. Frequent

Circulation Journal Vol.76, July 2012 1586 ONOUCHI Y

somatic mutations of the transcription factor ATBF1 in human pros- 53. McGovern DP, Gardet A, Törkvist L, Goyette P, Essers J, Taylor tate cancer. Nat Genet 2005; 37: 407 – 412. KD, et al. Genome-wide association identifies multiple ulcerative 32. Benjamin EJ, Rice KM, Arking DE, Pfeufer A, van Noord C, Smith colitis susceptibility loci. Nat Genet 2010; 42: 332 – 337. AV, et al. Variants in ZFHX3 are associated with atrial fibrillation in 54. Gregersen PK, Amos CI, Lee AT, Lu Y, Remmers EF, Kastner DL, individuals of European ancestry. Nat Genet 2009; 41: 879 – 881. et al. REL, encoding a member of the NF-kappaB family of tran- 33. Gudbjartsson DF, Holm H, Gretarsdottir S, Thorleifsson G, Walters scription factors, is a newly defined risk locus for rheumatoid arthri- GB, Thorgeirsson G, et al. A sequence variant in ZFHX3 on 16q22 tis. Nat Genet 2009; 41: 820 – 823. associates with atrial fibrillation and ischemic stroke. Nat Genet 55. Freudenberg J, Lee HS, Han BG, Shin HD, Kang YM, Sung YK, et al. 2009; 41: 876 – 878. Genome-wide association study of rheumatoid arthritis in Koreans: 34. Li C, Wang F, Yang Y, Fu F, Xu C, Shi L, et al. Significant associa- Population-specific loci as well as overlap with European suscepti- tion of SNP rs2106261 in the ZFHX3 gene with atrial fibrillation in bility loci. Arthritis Rheum 2011; 63: 884 – 893. a Chinese Han GeneID population. Hum Genet 2011; 129: 239 – 246. 56. Ito I, Kawasaki A, Ito S, Kondo Y, Sugihara M, Horikoshi M, et al. 35. Kim JJ, Hong YM, Sohn S, Jang GY, Ha KS, Yun SW, et al. A ge- Replication of association between FAM167A(C8orf13)-BLK re- nome-wide association analysis reveals 1p31 and 2p13.3 as suscep- gion and rheumatoid arthritis in a Japanese population. Ann Rheum tibility loci for Kawasaki disease. Hum Genet 2011; 129: 487 – 495. Dis 2010; 69: 936 – 937. 36. Jin W, Chang M, Sun SC. Peli: A family of signal-responsive E3 57. Orozco G, Eyre S, Hinks A, Bowes J, Morgan AW, Wilson AG. Study ubiquitin ligases mediating TLR signaling and T-cell tolerance. Cell of the common genetic background for rheumatoid arthritis and Mol Immunol 2012; 9: 113 – 122. systemic lupus erythematosus. Ann Rheum Dis 2011; 70: 463 – 468. 37. Chang M, Jin W, Chang JH, Xiao Y, Brittain GC, Yu J, et al. The 58. Deshmukh HA, Maiti AK, Kim-Howard XR, Rojas-Villarraga A, ubiquitin ligase Peli1 negatively regulates T cell activation and pre- Guthridge JM, Anaya JM, et al. Evaluation of 19 autoimmune dis- vents autoimmunity. Nat Immunol 2011; 12: 1002 – 1009. ease-associated loci with rheumatoid arthritis in a Colombian popu- 38. Tsai FJ, Lee YC, Chang JS, Huang LM, Huang FY, Chiu NC, et al. lation: Evidence for replication and gene-gene interaction. J Rheu- Identification of novel susceptibility loci for Kawasaki disease in a matol 2011; 38: 1866 – 1870. Han Chinese population by a genome-wide association study. PLoS 59. Hom G, Graham RR, Modrek B, Taylor KE, Ortmann W, Garnier S, One 2011; 6: e16853. et al. Association of systemic lupus erythematosus with C8orf13- 39. Wellcome Trust Case Control Consortium; Australo-Anglo-American BLK and ITGAM-ITGAX. N Engl J Med 2008; 358: 900 – 909. Spondylitis Consortium (TASC), Burton PR, Clayton DG, Cardon 60. Ito I, Kawasaki A, Ito S, Hayashi T, Goto D, Matsumoto I, et al. LR, Craddock N, et al. Association scan of 14,500 nonsynonymous Replication of the association between the C8orf13-BLK region and SNPs in four diseases identifies autoimmunity variants. Nat Genet systemic lupus erythematosus in a Japanese population. Arthritis 2007; 39: 1329 – 1337. Rheum 2009; 60: 553 – 558. 40. Australo-Anglo-American Spondyloarthritis Consortium (TASC), 61. Yang W, Ng P, Zhao M, Hirankarn N, Lau CS, Mok CC, et al. Popu- Reveille JD, Sims AM, Danoy P, Evans DM, Leo P, et al. Genome- lation differences in SLE susceptibility genes: STAT4 and BLK, but wide association study of ankylosing spondylitis identifies non-MHC not PXK, are associated with systemic lupus erythematosus in Hong susceptibility loci. Nat Genet 2010; 42: 123 – 127. Kong Chinese. Genes Immun 2009; 10: 219 – 226. 41. Genetic Analysis of Psoriasis Consortium & the Wellcome Trust Case 62. Han JW, Zheng HF, Cui Y, Sun LD, Ye DQ, Hu Z, et al. Genome- Control Consortium 2, Strange A, Capon F, Spencer CC, Knight J, wide association study in a Chinese Han population identifies nine et al. A genome-wide association study identifies new psoriasis sus- new susceptibility loci for systemic lupus erythematosus. Nat Genet ceptibility loci and an interaction between HLA-C and ERAP1. Nat 2009; 41: 1234 – 1237. Genet 2010; 42: 985 – 990. 63. Zhang Z, Zhu KJ, Xu Q, Zhang XJ, Sun LD, Zheng HF, et al. The 42. Sun LD, Cheng H, Wang ZX, Zhang AP, Wang PG, Xu JH, et al. association of the BLK gene with SLE was replicated in Chinese Association analyses identify six new psoriasis susceptibility loci in Han. Arch Dermatol Res 2010; 302: 619 – 624. the Chinese population. Nat Genet 2010; 42: 1005 – 1009. 64. Gourh P, Agarwal SK, Martin E, Divecha D, Rueda B, Bunting H, 43. Khor CC, Davila S, Breunis WB, Lee YC, Shimizu C, Wright VJ, et al. et al. Association of the C8orf13-BLK region with systemic sclerosis Genome-wide association study identifies FCGR2A as a susceptibil- in North-American and European populations. J Autoimmun 2010; ity locus for Kawasaki disease. Nat Genet 2011; 43: 1241 – 1246. 34: 155 – 162. 44. Nimmerjahn F, Ravetch JV. Fcγ receptors as regulators of immune 65. Ito I, Kawaguchi Y, Kawasaki A, Hasegawa M, Ohashi J, Kawamoto responses. Nature Rev Immunol 2008; 8: 34 – 47. M, et al. Association of the FAM167A-BLK region with systemic 45. Bruhns P, Iannascoli B, England P, Mancardi DA, Fernandez N, Jorieux sclerosis. Arthritis Rheum 2010; 62: 890 – 895. S, et al. Specificity and affinity of human Fcgamma receptors and 66. Coustet B, Dieudé P, Guedj M, Bouaziz M, Avouac J, Ruiz B, et al. their polymorphic variants for human IgG subclasses. Blood 2009; C8orf13-BLK is a genetic risk locus for systemic sclerosis and has 113: 3716 – 3725. additive effects with BANK1: Results from a large French cohort 46. Onouchi Y, Ozaki K, Burns JC, Shimizu C, Terai M, Hamada H, et al. and meta-analysis. Arthritis Rheum 2011; 63: 2091 – 2096. A genome-wide association study identifies three new risk loci for 67. Tomer Y, Concepcion E, Greenberg DA. A C/T single-nucleotide Kawasaki disease. Nat Genet 2012; 44: 517 – 521. polymorphism in the region of the CD40 gene is associated with 47. Lee YC, Kuo HC, Chang JS, Chang LY, Huang LM, Chen MR, et al. Graves’ disease. Thyroid 2002; 12: 1129 – 1135. Two new susceptibility loci for Kawasaki disease identified through 68. Mukai T, Hiromatsu Y, Fukutani T, Ichimura M, Kaku H, Miyake I, genome-wide association analysis. Nat Genet 2012; 44: 522 – 525. et al. A C/T polymorphism in the 5’ untranslated region of the CD40 48. Bewarder N, Weinrich V, Budde P, Hartmann D, Flaswinkel H, Reth gene is associated with later onset of Graves’ disease in Japanese. M, et al. In vivo and in vitro specificity of protein tyrosine kinases Endocr J 2005; 52: 471 – 477. for immunoglobulin G receptor (FcgammaRII) phosphorylation. Mol 69. Ban Y, Tozaki T, Taniyama M, Tomita M, Ban Y. Association of a Cell Biol 1996; 16: 4735 – 4743. C/T single-nucleotide polymorphism in the 5’ untranslated region of 49. Borowiec M, Liew CW, Thompson R, Boonyasrisawat W, Hu J, the CD40 gene with Graves’ disease in Japanese. Thyroid 2006; 16: Mlynarski WM, et al. Mutations at the BLK locus linked to maturity 443 – 446. onset diabetes of the young and beta-cell dysfunction. Proc Natl 70. Raychaudhuri S, Remmers EF, Lee AT, Hackett R, Guiducci C, Burtt Acad Sci USA 2009; 106: 14460 – 14465. NP, et al. Common variants at CD40 and other loci confer risk of 50. Jacobson EM, Concepcion E, Oashi T, Tomer Y. A Graves’ disease- rheumatoid arthritis. Nat Genet 2008; 40:1216 – 1223. associated Kozak sequence single-nucleotide polymorphism enhanc- 71. Orozco G, Eyre S, Hinks A, Ke X, Wellcome Trust Case Control es the efficiency of CD40 gene translation: A case for translational consortium YEAR Consortium, Wilson AG, et al. Association of pathophysiology. Endocrinology 2005; 146: 2684 – 2691. CD40 with rheumatoid arthritis confirmed in a large UK case-control 51. Asano K, Matsushita T, Umeno J, Hosono N, Takahashi A, Kawaguchi study. Ann Rheum Dis 2010; 69: 813 – 816. T, et al. A genome-wide association study identifies three new sus- 72. Vazgiourakis VM, Zervou MI, Choulaki C, Bertsias G, Melissourgaki ceptibility loci for ulcerative colitis in the Japanese population. Nat M, Yilmaz N, et al. A common SNP in the CD40 region is associ- Genet 2009; 41: 1325 – 1329. ated with systemic lupus erythematosus and correlates with altered 52. International Consortium for Systemic Lupus Erythematosus Genet- CD40 expression: Implications for the pathogenesis. Ann Rheum Dis ics (SLEGEN), Harley JB, Alarcón-Riquelme ME, Criswell LA, Jacob 2011; 70: 2184 – 2190. CO, Kimberly RP, et al. Genome-wide association scan in women 73. Australia and New Zealand Multiple Sclerosis Genetics Consortium with systemic lupus erythematosus identifies susceptibility variants (ANZgene). Genome-wide association study identifies new multiple in ITGAM, PXK, KIAA1542 and other loci. Nat Genet 2008; 40: sclerosis susceptibility loci on 12 and 20. Nat Genet 204 – 210. 2009; 41: 824 – 828.

Circulation Journal Vol.76, July 2012