Consortium-Based Genetic Studies of Kawasaki Disease in Korea: Korean Kawasaki Disease Genetics Consortium

Abstract

In order to perform large-scale genetic studies of Kawasaki disease (KD) in Korea, the Korean Kawasaki Disease Genetics Consortium (KKDGC) was formed in 2008 with 10 hospitals. Since the establishment of KKDGC, there has been a collection of clinical data from a total of 1198 patients, and approximately 5 mL of blood samples per patient (for genomic deoxyribonucleic acid and plasma isolation), using a standard clinical data collection form and a nation-wide networking system for blood sample pick-up. In the clinical risk factor analysis using the collected clinical data of 478 KD patients, it was found that incomplete KD type, intravenous immunoglobulin (IVIG) non-responsiveness, and long febrile days are major risk factors for coronary artery lesions development, whereas low serum albumin concentration is an independent risk factor for IVIG non-responsiveness. In addition, we identified a KD susceptibility locus at 1p31, a coronary artery aneurysm locus (KCNN2 gene), and the causal variant in the C-reactive protein (CRP) promoter region, as determining the increased CRP levels in KD patients, by means of genome-wide association studies. Currently, this consortium is continually collecting more clinical data and genomic samples to identify the clinical and genetic risk factors via a single nucleotide polymorphism chip and exome sequencing, as well as collaborating with several international KD genetics teams. The consortium-based approach for genetic studies of KD in Korea will be a very effective way to understand the unknown etiology and causal mechanism of KD, which may be affected by multiple genes and environmental factors.

Keywords: Genome-wide association study; Mucocutaneous lymph node syndrome; Polymorphism, single nucleotide.

Fig. 1. Participating hospitals in KKDGC and the numbers of sample collected. A total of 517 and 681 KD case samples were collected during the first (May 2008 to February 2010) and second (April 2012 to September 2014) KKDGC, respectively. KKDGC: Korean Kawasaki Disease Genetics Consortium, KD: Kawasaki disease.

Fig. 2. Work process of KKDGC to collect the clinical data and genomic DNA samples. Each patient's blood sample and clinical data were collected using standard protocol. KKDGC: Korean Kawasaki Disease Genetics Consortium, DNA: deoxyribonucleic acid, AMC: Asan Medical Center, SCL: Seoul Clinical Laboratories, DB: database, IRB: institutional review board, ACD: acid citrate dextrose, EDTA: ethylenediamine tetraacetic acid, RT: room temperature, EBV: Epstein-Barr virus.

Fig. 3. Clinical data collection sheet for KD. A total of 41 clinical variables were collected per patient. KD: Kawasaki disease, ID: identification, IVIG: intravenous immunoglobulin, CRP: C-reactive protein, ESR: erythrocyte sedimentation rate, Hb: hemoglobulin, AST: aspartate aminotransferase, ALT: alanine aminotransferase, IU: international unit, L: liter.

Fig. 4. Cell proliferation assay after in vitro IG treatment in KD patient-derived B cell lines (A), macrophage-like cell line (U937) (B) and neutrophil-like cell (HL60) (C). Each cell was treated with various concentrations of IG for 48 hr and cell proliferation assay was performed using commercial kit. IG: immunoglobulin, KD: Kawasaki disease.

Fig. 5. Overview of GWAS performed by KKDGC. The results of GWAS were published. GWAS: genome-wide association study, KKDGC: Korean Kawasaki Disease Genetics Consortium, KD; Kawasaki disease, M: male, F: female, SNP: single nucleotide polymorphism, CAL: coronary artery lesion, IVIG: intravenous immunoglobulin, CRP: C-reactive protein, WBC: white blood cell, Hb: hemoglobulin, AST: aspartate aminotransferase, ALT: alanine aminotransferase.