Sex-Specific Susceptibility Loci Associated With Coronary Artery Aneurysms in Patients With Kawasaki Disease.

BACKGROUND AND OBJECTIVES: Kawasaki disease (KD) is an acute vasculitis that primarily affects children under age 5 years. Approximately 20-25% of untreated children with KD and 3-5% of those treated with intravenous immunoglobulin therapy develop coronary artery aneurysms (CAAs). The prevalence of CAAs is much higher in male than in female patients with KD, but the underlying factors contributing to susceptibility to CAAs in patients with KD remain unclear. This study aimed to identify sex-specific susceptibility loci associated with CAAs in KD patients. METHODS: A sex-stratified genome-wide association study (GWAS) was performed using previously obtained GWAS data from 296 KD patients and a new replication study in an independent set of 976 KD patients by comparing KD patients without CAA (controls) and KD patients with aneurysms (internal diameter ≥5 mm) (cases). RESULTS: Six male-specific susceptibility loci, PDE1C, NOS3, DLG2, CPNE8, FUNDC1, and GABRQ (odds ratios [ORs], 2.25-9.98; p=0.00204-1.96×10-6), and 2 female-specific susceptibility loci, SMAD3 (OR, 4.59; p=0.00016) and IL1RAPL1 (OR, 4.35; p=0.00026), were significantly associated with CAAs in patients with KD. In addition, the numbers of CAA risk alleles additively contributed to the development of CAAs in patients with KD. CONCLUSIONS: A sex-stratified GWAS identified 6 male-specific (PDE1C, NOS3, DLG2, CPNE8, FUNDC1, and GABRQ) and 2 female-specific (SMAD3 and IL1RAPL1) CAA susceptibility loci in patients with KD.

Identification of B-cell-related HSPG2 and CDSN as susceptibility loci for Kawasaki disease.

Kawasaki disease (KD) is an acute pediatric vasculitis that predominantly affects children under the age of 5 years. To date, genome-wide association studies (GWAS) have identified several KD susceptibility genes (e.g., BLK, CD40, FCGR2A, BCL2L11, and IGHV), which are mainly involved in B cell immunity. In this study, we aimed to identify additional KD susceptibility genes mainly involved in B cell development and functions by analyzing our previous GWAS data and conducting a replication study using new sample. Initially, we selected 30 single nucleotide polymorphisms (SNPs) in B-cell-related genes that were significantly (P < 0.01) associated with KD in our previous GWAS analysis of 247 KD cases with complete type and 1,000 healthy controls. Replication study was performed by genotyping the new 837 KD case samples with Fluidigm system and comparing them with 3,553 control genotypes. Among the 30 candidate SNPs, two were significantly associated with KD (P < 0.001) in the replication study. An even greater association between these SNPs and KD was observed in the combined analysis of GWAS and replication samples: odds ratio (OR) = 1.97 (P = 8.61 × 10-6) for rs2270699 (nonsynonymous SNP: c.10588C > T, p.Arg3530Trp) in the heparan sulfate proteoglycan 2 (HSPG2) gene and OR = 1.28 (P = 1.34 × 10-6) for rs3130992 (intronic SNP) in both the corneodesmosin (CDSN) and psoriasis susceptibility 1 candidate 1 (PSORS1C1) genes. These results suggest that the B-cell-related genes, HSPG2 and CDSN or PSORS1C1, play a role in the development of KD.

IgA Levels Are Associated with Coronary Artery Lesions in Kawasaki Disease.

BACKGROUND AND OBJECTIVES: Kawasaki disease (KD) is an acute systemic vasculitis that affects the coronary arteries. Abnormal immune reactions are thought to contribute to disease pathogenesis. The effect of immunoglobulin (Ig) isotype (IgG, IgA, IgM, and IgE) on inflammatory data and clinical outcomes of patients with KD was examined. METHODS: Ig levels in 241 patients with KD were measured during the acute, subacute, convalescent, and normal phases of the disease. RESULTS: Compared with reference Ig values, IgG, IgA, and IgM levels were significantly higher in the subacute phase, while IgE levels were elevated in 73.9% (178/241) of patients with KD in all clinical phases. However, high IgE levels were not associated with clinical outcomes, including intravenous immunoglobulin unresponsiveness and coronary artery lesions (CALs). Significantly more CALs were observed in the high IgA group than in the normal IgA group (44.7% vs. 20.8%, respectively; p<0.01). In addition, IgA levels in the acute phase (p=0.038) were 2.2-fold higher, and those in the subacute phase were 1.7-fold higher (p <0.001), in the CAL group than in the non-CAL group. IgA concentrations increased along with the size of the coronary artery aneurysm (p <0.001). Furthermore, there was a strong correlation between IgA levels and CAL size (r=0.435, p<0.001), with a high odds ratio of 2.58 (p=0.022). CONCLUSIONS: High IgA levels in patients with KD are prognostic for the risk of CALs.

Identification of rare coding variants associated with Kawasaki disease by whole exome sequencing.

Kawasaki disease (KD) is an acute pediatric vasculitis that affects genetically susceptible infants and children. To identify coding variants that influence susceptibility to KD, we conducted whole exome sequencing of 159 patients with KD and 902 controls, and performed a replication study in an independent 586 cases and 732 controls. We identified five rare coding variants in five genes (FCRLA, PTGER4, IL17F, CARD11, and SIGLEC10) associated with KD (odds ratio [OR], 1.18 to 4.41; p = 0.0027-0.031). We also performed association analysis in 26 KD patients with coronary artery aneurysms (CAAs; diameter > 5 mm) and 124 patients without CAAs (diameter < 3 mm), and identified another five rare coding variants in five genes (FGFR4, IL31RA, FNDC1, MMP8, and FOXN1), which may be associated with CAA (OR, 3.89 to 37.3; p = 0.0058-0.0261). These results provide insights into new candidate genes and genetic variants potentially involved in the development of KD and CAA.

Epidemiology of Kawasaki Disease in South Korea: A Nationwide Survey 2015-2017.

BACKGROUND: This study aimed to investigate recent epidemiologic features of Kawasaki disease (KD) in South Korea. METHODS: The ninth triennial nationwide questionnaire survey collected data on the demographic findings, symptoms and signs, treatment patterns and coronary artery complications of acute-phase KD occurred in 2015-2017 from 98 hospitals with pediatric residency programs and 108 community hospitals without residency programs. RESULTS: We received data from 93 of the 98 hospitals (response rate: 94.9%) with residency programs and 75 of the 108 community-based children's hospitals (response rate: 69.4%) without residency programs. In the 3-year survey period, a total of 15,378 (5449 in 2015, 5171 in 2016 and 4758 in 2017) cases of KD were reported. The mean age at diagnosis was 33.0 ± 24.8 months (range: 0-205 months), and the male-to-female ratio was 1.41:1. The overall KD incidence was 196.9 (202.2 in 2015, 197.1 in 2016 and 191.0 in 2017) per 100,000 younger than 5 years population. Recurrent cases were 4.85%. KD occurred more frequently during winter (December-January) and late spring (May-June). Intravenous immunoglobulin (IVIG) was administered to 95% of the patients; nonresponder rate for the first IVIG was 14.8%. Coronary artery aneurysms and giant coronary artery aneurysms (internal diameter >8 mm) occurred in 1.7% and 19 patients, respectively. Two patients died due to multiorgan failure and hepatic encephalopathy. CONCLUSION: Peak incidence of KD in South Korea was 202.2 per 100,000 younger than 5 years population (2015), and the incidence of giant coronary artery aneurysm decreased to 0.09% (2017).

Association of the IL16 Asn1147Lys polymorphism with intravenous immunoglobulin resistance in Kawasaki disease.

Kawasaki disease (KD) is an acute, self-limited vasculitis, mainly affecting children younger than 5 years old, with accompanying fever and signs of mucocutaneous inflammation. Intravenous immunoglobulin (IVIG) is the standard treatment for KD; however, ~15% of patients are resistant to IVIG treatment. To identify protein coding genetic variants influencing IVIG resistance, we re-analyzed our previous genome-wide association study (GWAS) data from 296 patients with KD, including 101 IVIG non-responders and 195 IVIG responders. Five nonsynonymous SNPs (nsSNPs) in five immune-related genes, including a previously reported SAMD9L nsSNP (rs10488532; p.Val266Ile), were associated with IVIG non-response (odds ratio [OR] = 1.89-3.46, P = 0.0109-0.0035). In a replication study of the four newly-identified nsSNPs, only one in the interleukin 16 (IL16) gene (rs11556218, p.Asn1147Lys) showed a trend of association with IVIG non-response (OR = 1.54, P = 0.0078). The same IL16 nsSNP was more significantly associated with IVIG non-response in combined analysis of all data (OR = 1.64, P = 1.25 × 10-4). Furthermore, risk allele combination of the IL16 CT and SAMD9L TT nsSNP genotypes exhibited a very strong effect size (OR = 9.19, P = 3.63 × 10-4). These results implicate IL16 as involved in the mechanism of IVIG resistance in KD.

Identification of SAMD9L as a susceptibility locus for intravenous immunoglobulin resistance in Kawasaki disease by genome-wide association analysis.

Kawasaki disease (KD) is a systemic vasculitis affecting infants and children; it manifests as fever and signs of mucocutaneous inflammation. Intravenous immunoglobulin (IVIG) treatment effectively attenuates the fever and systemic inflammation. However, 10-20% patients are unresponsive to IVIG. To identify genetic variants influencing IVIG non-response in KD, a genome-wide association study (GWAS) and a replication study were performed using a total of 148 IVIG non-responders and 845 IVIG-responders in a Korean population. rs28662 in the sterile alpha motif domain-containing protein 9-like (SAMD9L) locus showed the most significant result in the joint analysis of GWAS and replication samples (odds ratio (OR) = 3.47, P = 1.39 × 10-5). The same SNP in the SAMD9L locus was tested in the Japanese population, and it revealed a more significant association in a meta-analysis with Japanese data (OR = 4.30, P = 5.30 × 10-6). These results provide new insights into the mechanism of IVIG response in KD.

Identification of the TIFAB Gene as a Susceptibility Locus for Coronary Artery Aneurysm in Patients with Kawasaki Disease.

Kawasaki disease (KD) is a self-limiting systemic vasculitis of unknown etiology. KD is often complicated by coronary artery aneurysms (CAAs), which develop in about 20-25% of untreated children and 3-5% of children treated with intravenous immunoglobulin therapy. To identify the risk loci for CAA susceptibility in patients with KD, we performed a genome-wide association study (GWAS) using our previous Illumina HumanOmni1-Quad BeadChip data (296 KD patients) and a new replication study in an independent sample set (713 KD patients) by grouping KD patients without CAA (control) versus KD patients with extremely large aneurysms (diameter ≥ 5 mm) (case). Among 44 candidate single -nucleotide polymorphisms (SNPs) selected from the initial GWAS data (33 cases vs. 215 controls), a SNP (rs899162) located 7 kb upstream of the TIFAB gene on chromosome five was replicated in an independent sample (12 cases vs. 532 controls). In the combined analysis (45 cases vs. 747 controls), the SNP (rs899162) showed a highly significant association with CAA formation (diameter ≥ 5 mm) in patients with KD (odds ratio = 3.20, 95% confidence interval = 2.02-5.05, Pcombined = 1.95 × 10-7). These results indicate that the TIFAB gene may act as a CAA susceptibility locus in patients with KD.

High antistreptolysin O titer is associated with coronary artery lesions in patients with Kawasaki disease.

PURPOSE: In Kawasaki disease (KD) patients, coronary artery complications, incomplete and refractory types occur more frequently in patients with streptococcal or other bacterial/viral infections. Recently, we observed a higher incidence of coronary lesions in KD patients with high anti-streptolysin O (ASO) titer. Therefore, we hypothesized that KD patients diagnosed with concurrent streptococcal infection have poor prognosis, with respect to treatment response and development of coronary artery lesions. METHODS: A retrospective review was performed in 723 patients with KD who were admitted to 2 major hospitals between June 2010 and September 2017. RESULTS: Among 723 patients with KD, 11 initially showed an elevated ASO titer (>320 IU/mL) or elevated follow-up ASO titer after treatment. Of these patients, 5 showed no response to the first intravenous immunoglobulin treatment, 3 had abnormalities of the coronary arteries. This is a significantly higher proportion of patients with a high ASO titer (n=3, 27.3%) than those with a normal ASO titer (n=53, 7.4%; P=0.047). A severe clinical course was seen in 81.8% of patients in the high ASO group versus 14.5% of patients in the normal ASO group. CONCLUSION: It is not certain whether acute streptococcal infection may cause KD, but this study revealed that KD with high ASO titers showed higher rates of severe clinical course. It may be helpful to analyze concurrent streptococcal infection in patients with a severe clinical course.

Assessment of the Clinical Heterogeneity of Kawasaki Disease Using Genetic Variants of BLK and FCGR2A.

BACKGROUND AND OBJECTIVES: Patients with Kawasaki disease (KD) are clinically heterogeneous because its diagnosis is based solely on clinical observation and there are no definitive biomarkers. We dissected the clinical heterogeneity of KD patients using the KD-associated genetic variants. METHODS: We performed a genetic association analysis in several KD subgroups categorized by clinical characteristics using the KD-associated variants of the B lymphoid tyrosine kinase (BLK; rs6993775) and Fc gamma receptor II a (FCGR2A; rs1801274) in a large number of case (n=1,011) and control (n=4,533) samples. RESULTS: BLK and FCGR2A were very significantly associated with KD in Korean KD patients (odds ratio [OR],1.48; p=4.63×10⁻¹¹ for BLK, and OR, 1.26; p=1.42×10⁻4 for FCGR2A). However, in KD subgroup analysis, we found that neither BLK nor FCGR2A were associated with either incomplete Kawasaki disease (iKD) type patients or those older than 5 years of age (p>0.2), suggesting that patients with iKD or those older than 5 years of age are a unique subgroup of KD. In genetic association analysis after excluding iKD patients and those older than 5 years old, we found that BLK was associated with all KD subgroups, whereas FCGR2A was specifically associated with male KD patients younger than 1 year of age (OR, 2.22; p=2.35×10⁻5). CONCLUSIONS: KD is a clinically and genetically heterogeneous disease. These findings will provide new insights into the clinical and genetic heterogeneity of KD.

Infliximab Treatment for Intravenous Immunoglobulin-resistant Kawasaki Disease: a Multicenter Study in Korea.

BACKGROUND AND OBJECTIVES: We investigated the status of infliximab use in intravenous immunoglobulin (IVIG)-resistant Kawasaki disease (KD) patients and the incidence of coronary artery aneurysms (CAAs) according to treatment regimens. METHODS: Between March 2010 and February 2017, 16 hospitals participated in this study. A total of 102 (32.3±19.9 months, 72 males) who received infliximab at any time after first IVIG treatment failure were enrolled. Data were retrospectively collected using a questionnaire. RESULTS: Subjects were divided into two groups according to the timing of infliximab administration. Early treatment (group 1) had shorter fever duration (10.5±4.4 days) until infliximab infusion than that in late treatment (group 2) (16.4±4.5 days; p<0.001). We investigated the response rate to infliximab and the incidence of significant CAA (z-score >5). Overall response rate to infliximab was 89/102 (87.3%) and the incidence of significant CAA was lower in group 1 than in group 2 (1/42 [2.4%] vs. 17/60 [28.3%], p<0.001). CONCLUSIONS: This study suggests that the early administration of infliximab may reduce the incidence of significant CAA in patients with IVIG-resistant KD. However, further prospective randomized studies with larger sample sizes are required.

Identification of LEF1 as a Susceptibility Locus for Kawasaki Disease in Patients Younger than 6 Months of Age.

Kawasaki disease (KD) is an acute febrile vasculitis predominately affecting infants and children. The dominant incidence age of KD is from 6 months to 5 years of age, and the incidence is unusual in those younger than 6 months and older than 5 years of age. We tried to identify genetic variants specifically associated with KD in patients younger than 6 months or older than 5 years of age. We performed an age-stratified genome-wide association study using the Illumina HumanOmni1-Quad BeadChip data (296 cases vs. 1,000 controls) and a replication study (1,360 cases vs. 3,553 controls) in the Korean population. Among 26 candidate single nucleotide polymorphisms (SNPs) tested in replication study, only a rare nonsynonymous SNP (rs4365796: c.1106C＞T, p.Thr369Met) in the lymphoid enhancer binding factor 1 (LEF1) gene was very significantly associated with KD in patients younger than 6 months of age (odds ratio [OR], 3.07; pcombined = 1.10 × 10-5), whereas no association of the same SNP was observed in any other age group of KD patients. The same SNP (rs4365796) in the LEF1 gene showed the same direction of risk effect in Japanese KD patients younger than 6 months of age, although the effect was not statistically significant (OR, 1.42; p = 0.397). This result indicates that the LEF1 gene may play an important role as a susceptibility gene specifically affecting KD patients younger than 6 months of age.

An infant presenting with Kawasaki disease following immunization for influenza: A case report.

Kawasaki disease (KD) is a childhood vascular disorder of unknown etiology. Concerns have recently been raised regarding vaccinations as a potential risk factor for KD. In addition, various forms of vasculitis have been reported as adverse events following administration after various vaccines. Patients exhibiting post vaccination KD have previously been described; however, thus far, to the best of our knowledge, only one patient exhibiting post influenza vaccination KD has been reported in Japan. The present study describes a case of KD 24 h after immunization with influenza in an infant (age, 18 months) following 6 days of high fever, a body rash that had persisted for 2 days and nonsuppurative bilateral conjunctivitis. To the best of the authors' knowledge, this is the first reported case in Korea and the present study reviews various recent studies regarding vasculitis following vaccination and the causal association between them.

A genome-wide association analysis identifies NMNAT2 and HCP5 as susceptibility loci for Kawasaki disease.

Kawasaki disease (KD), a systemic vasculitis of infants and children, manifests as fever and mucocutaneous inflammation. Although its etiology is largely unknown, the epidemiological data suggest that genetic factors are important in KD susceptibility. To identify genetic variants influencing KD susceptibility, we performed a genome-wide association study (GWAS) and replication study using a total of 915 children with KD and 4553 controls in the Korean population. Six single-nucleotide polymorphisms (SNPs) in three loci were associated significantly with KD susceptibility (P<1.0 × 10-5), including the previously reported BLK locus (rs6993775, odds ratio (OR)=1.52, P=2.52 × 10-11). The other two loci were newly identified: NMNAT2 on chromosome 1q25.3 (rs2078087, OR=1.33, P=1.15 × 10-6) and the human leukocyte antigen (HLA) region on chromosome 6p21.3 (HLA-C, HLA-B, MICA and HCP5) (rs9380242, rs9378199, rs9266669 and rs6938467; OR=1.33-1.51, P=8.93 × 10-6 to 5.24 × 10-8). Additionally, SNP rs17280682 in NLRP14 was associated significantly with KD with a family history (18 cases vs 4553 controls, OR=6.76, P=5.46 × 10-6). These results provide new insights into the pathogenesis and pathophysiology of KD.