Kawasaki disease is a systemic vasculitis of unknown etiology, with clinical observations suggesting a substantial genetic contribution to disease susceptibility. We conducted a genome-wide association study and replication analysis in 2,173 individuals with Kawasaki disease and 9,383 controls from five independent sample collections. Two loci exceeded the formal threshold for genome-wide significance. The first locus is a functional polymorphism in the IgG receptor gene FCGR2A (encoding an H131R substitution) (rs1801274; P = 7.35 × 10(-11), odds ratio (OR) = 1.32), with the A allele (coding for histadine) conferring elevated disease risk. The second locus is at 19q13, (P = 2.51 × 10(-9), OR = 1.42 for the rs2233152 SNP near MIA and RAB4B; P = 1.68 × 10(-12), OR = 1.52 for rs28493229 in ITPKC), which confirms previous findings(1). The involvement of the FCGR2A locus may have implications for understanding immune activation in Kawasaki disease pathogenesis and the mechanism of response to intravenous immunoglobulin, the only proven therapy for this disease.

Kawasaki disease (KD) is an acute self-limited vasculitis of infants and children that manifests as fever and signs of mucocutaneous inflammation. Coronary artery aneurysms develop in approximately 15-25% of untreated children. Although the etiology of KD is largely unknown, epidemiologic data suggest the importance of genetic factors in the susceptibility to KD. In order to identify genetic variants that influence KD susceptibility, we performed a genome-wide association study (GWAS) using Affymetrix SNP array 6.0 in 186 Korean KD patients and 600 healthy controls; 18 and 26 genomic regions with one or more sequence variants were associated with KD and KD with coronary artery lesions (CALs), respectively (p < 1 × 10(-5)). Of these, one locus on chromosome 1p31 (rs527409) was replicated in 266 children with KD and 600 normal controls (odds ratio [OR] = 2.90, 95% confidence interval [CI] = 1.85-4.54, P (combined) = 1.46 × 10(-6)); and a PELI1 locus on chromosome 2p13.3 (rs7604693) was replicated in 86 KD patients with CALs and 600 controls (OR = 2.70, 95% CI = 1.77-4.12, P (combined) = 2.00 × 10(-6)). These results implicate a locus in the 1p31 region and the PELI1 gene locus in the 2p13.3 region as susceptibility loci for KD and CALs, respectively.

Background After the global epidemic of coronavirus disease 2019 (COVID-19), lifestyle changes to curb the spread of COVID-19 (e.g., wearing a mask, hand washing, and social distancing) have also affected the outbreak of other infectious diseases. However, few studies have been conducted on whether the incidence of gastrointestinal infections has changed over the past year with COVID-19. In this study, we examined how the incidence of gastrointestinal infections has changed since COVID-19 outbreak through open data. Methods We summarized the data on the several viruses and bacteria that cause gastrointestinal infections from the open data of the Korea Disease Control and Prevention Agency for 3 years from March 2018 to February 2021 (from Spring 2018 to Winter 2020). Moreover, we confirmed three most common legal gastrointestinal infectious pathogens from March 2016. Results From March 2020, when the COVID-19 epidemic was in full swing and social distancing and personal hygiene management were heavily emphasized, the incidence of infection from each virus was drastically decreased. The reduction rates compared to the averages of the last 2 years were as follows: total viruses 31.9%, norovirus 40.2%, group A rotavirus 31.8%, enteric adenovirus 13.4%, astrovirus 7.0%, and sapovirus 12.2%. Among bacterial pathogens, the infection rates of Campylobacter and Clostridium perfringens did not decrease but rather increased in some periods when compared to the average of the last two years. The incidence of nontyphoidal Salmonella, Staphylococcus aureus , or enteropathogenic Escherichia coli somewhat decreased but not significantly compared to the previous two years. Conclusion The incidence of infection from gastrointestinal viruses, which are mainly caused by the fecal-to-oral route and require direct contact among people, was significantly reduced, whereas the incidence of bacterial pathogens, which have food-mediated transmission as the main cause of infection, did not decrease significantly.

MicroRNAs (miRNAs) are small, non-coding RNAs that regulate the expression of protein-coding genes. Recently, miRNA levels have been used as a novel non-invasive biomarker for the diagnosis of various diseases. We aimed to identify serum miRNAs elevated in patients with Kawasaki disease (KD) and to explore the potential biological function of identified candidate miRNAs. Serum specimens were collected from children with KD (n = 12) and healthy controls (n = 6). miRNA microarray assays were performed using the PANArray™ miRNA expression profiling kit (PANAGENE Co., Daejeon, Korea). We used TargetScan and the database for annotation, visualization, and integrated discovery program to obtain a list of enriched biological pathways targeted by miRNAs elevated in KD patients. As a result, miR-200c and miR-371-5p were significantly upregulated in the KD group compared with the control group (p = 0.032 in both). By using TargetScan, we obtained a list of 421 and 542 genes predicted to be targeted by miR-200c and miR-371, respectively, and these genes were significantly (p < 0.05) clustered in 17 and 3 pathways, respectively. Many of them are major pathways involved in inflammatory responses. The present data support the hypothesis that the inflammatory response is a crucial mechanism for pathogenesis of KD, and miRNAs might be the main regulators of this inflammatory response.

Background Intussusception is a gastrointestinal condition in which early treatment is critical. Although its epidemiology and comorbidities have been studied, few studies have included the entire pediatric population of a country. Therefore, we aimed to analyze the epidemiologic features of pediatric intussusception patients and identify comorbidities associated with intussusception in South Korea, using the public health database. Methods We analyzed the data of children below 18 years of age, from the national database of South Korea, who were diagnosed with intussusception and managed such as air reduction or surgical methods from 2008 to 2016. Patients were categorized into six groups based on the comorbid diseases. Patients with structural lesion in gastrointestinal tract were divided diagnosis or diagnosis code. Results The number of patients diagnosed with intussusception were 25,023 (16,024 males, 64.0%). Of them, the highest percentage was patients aged between 2 and 36 months (20,703; 82.7%). The incidence per 100,000 individuals aged up to 2 years was 196.7. The number of males were 16,024 (64.0%) and were almost twice the number of 8999 (36.0%) female patients. The maximum number of cases ( n = 2517; 10.1%) were seen in September, followed by July ( n = 2469; 9.9%). In February, the number of cases was lowest at 1448 (5.8%) patients ( P < 0.001). The number of patients with structural lesions of the gastrointestinal tract that could lead to intussusception was 1207 (4.8%), while patients with acute gastrointestinal infectious disease were 4541 (18.1%). Among the structural lesions of the gastrointestinal tract that could be the leading cause of intussusception, lymphadenopathy was the most common, seen in 462 (56.6%) patients and an appendix-related condition was seen in 260 (31.9%) patients. Infectious diseases were more common in the younger children, while systemic diseases were more common in the older. Conclusion We confirmed that pediatric intussusception in South Korea shows a seasonal tendency, which is age-dependent and is associated with an exposure to infectious agents. Some infectious pathogens and underlying diseases might play an important role in the pathophysiology of intussusception.

Although antenatal diagnostic technique has considerably improved, precise detection and proper management of the neonate with congenital heart disease (CHD) is always a great concern to pediatricians. Congenital cardiac malformations vary from benign to serious conditions such as complete transposition of the great arteries (TGA), critical pulmonary and aortic valvular stenosis/atresia, hypoplastic left heart syndrome (HLHS), obstructed total anomalous pulmonary venous return (TAPVR), which the baby needs immediate diagnosis and management for survival. Unfortunately, these life threatening heart diseases may not have obvious evidence early after birth, most of the clinical and physical findings are nonspecific and vague, which makes the diagnosis difficult. High index of suspicion and astute acumen are essential to decision making. When patent ductus arteriosus (PDA) is opened widely, many serious malformations may not be noticed easily in the early life, but would progress as severe acidosis/shock/cyanosis or even death as PDA constricts after few hours to days. Ductus dependent congenital cardiac lesions can be divided into the ductus dependent systemic or pulmonary disease, but physiologically quite different from each other and treatment strategy has to be tailored to the clinical status and cardiac malformations. Inevitably early presentation is often regarded as a medical emergency. Differential diagnosis with inborn error metabolic disorders, neonatal sepsis, persistent pulmonary hypertension of the newborn (PPHN) and other pulmonary conditions are necessary. Urgent identification of the newborn at such high risk requires timely referral to a pediatric cardiologist, and timely intervention is the key in reducing mortality and morbidity. This following review deals with the clinical presentations, investigative modalities and approach to management of congenital cardiac malformations presenting in the early life.

Kawasaki disease (KD) is the most common cause of acquired heart disease in children. Intravenous immunoglobulin (IVIG) is the standard therapy for KD, but more than 10% of KD patients do not respond to IVIG and are at high risk for the development of coronary artery lesions (CALs). To identify clinical and genetic risk factors associated with CAL development and IVIG nonresponsiveness, this study analyzed the clinical data for 478 Korean KD patients. Multivariate logistic regression analysis showed that incomplete KD, IVIG nonresponse, fever duration of 7 days or longer, and the CC/AC genotypes of the rs7604693 single nucleotide polymorphism (SNP) in the PELI1 gene were significantly associated with the development of CALs, with odds ratios (ORs) ranging from 2.06 to 3.04. The risk of CAL formation was synergistically increased by the addition of individual risk factors, particularly the genetic variant in the PELI1 gene. Multivariate analysis also showed that a serum albumin level of 3.6 g/dl or lower was significantly associated with nonresponsiveness to IVIG [OR, 2.76; 95% confidence interval (CI), 1.34-5.68; P = 0.006]. Conclusively, incomplete KD, IVIG nonresponsiveness, long febrile days, and the rs7604693 genetic variant in the PELI1 gene are major risk factors for the development of CALs, whereas low serum albumin concentration is an independent risk factor for IVIG nonresponsiveness.

This study was undertaken to determine the genotype variability of human metapneumovirus (hMPV) and its circulation pattern over a 3.5-year period, and to evaluate its clinical characteristics in Korean children. We investigated 4599 pediatric patients who were referred for a routine respiratory virus test by RT-PCR. hMPV genotype analyses were performed using a nested PCR-restriction fragment length polymorphism assay. Clinical and laboratory data obtained from medical records were reviewed retrospectively. Of the 4599 samples tested, 325 (7.1%) were positive for hMPV, and the co-infection rate among these 325 was 16%. Nested PCR-restriction fragment length polymorphism analysis clearly identified four of the five hMPV genotypes (A2a, A2b, B1, and B2) in 97.8%. The predominant genotype of hMPV changed over the 3.5-year study period from genotype A2a to B2 and then back to A2a. The most common genotype was A2a (214/325, 65.8%). Evidence of recurrent infection was obtained in one child only. Lymphocytosis was more frequent in children with a co-infection, but sputum production was less frequent than in children with a single infection. In genotype A2a hMPV-infected children, sneezing and neutrophilia were more frequent than in genotype B1 or B2 hMPV-infected children. This study broadens knowledge regarding the prevalence, the seasonal incidence, the occurrences of co-infection and re-infection, and the genotype diversity of hMPV in Korea.