Background and aims: Although paediatric Crohn’s disease [CD] has a different phenotype and clinical course to adult CD, its clinical features and surgical risks are poorly defined, especially in Asian countries. The aim of this study was to investigate the clinical features and long-term outcomes of paediatric CD in a Korean population. Methods: We retrospectively analysed 594 patients who were younger than 18 years of age at CD diagnosis between 1987 and 2013. Patient characteristics at diagnosis according to the Paris classification and clinical courses were analysed. Results: The male-to-female ratio was 2.4:1 and the median age at CD diagnosis was 15 years [range, 2–17 years]. A positive first-degree family history of inflammatory bowel disease was present in 30 patients [5.1%]. Sixty-seven patients [11.3%] showed growth impairment. The cumulative probabilities of perianal fistula at 1, 5 and 10 years after diagnosis were 50.3%, 54.9% and 57.6%, respectively. The cumulative probabilities of anti-tumour necrosis factor treatment at 1, 5, 10 and 20 years after diagnosis were 10.7%, 25.8%, 41.8% and 76.3%, respectively. The cumulative probabilities of intestinal resection at 1, 5, 10 and 20 years after diagnosis were 4.5%, 17.2%, 33.9% and 62.9 %, respectively. In multivariate analysis, complicated behaviour and isolated colonic location [L2] at diagnosis were associated with an increased and decreased risk of intestinal resection, respectively. Conclusions: Our study is the largest Asian paediatric study which applied the Paris classification to patients. This study provides detailed information on disease phenotype and long-term clinical outcomes in a large cohort of Asian children with CD.

Interleukin-10 receptor [IL10R] mutations are associated with severe childhood inflammatory bowel disease [IBD]. Two unrelated patients who died of very early-onset severe IBD and sepsis were identified as harbouring the same compound heterozygous mutations in IL10RA [p.R101W; p.T179T]. A third patient was found to be homozygous for p.T179T. The missense change of p.R101W has been reported. The synonymous change of p.T179T, with a minor allele frequency of 0.035% in the population, was novel. The p.T179T mutation was located before the 5′ splice donor site, leading to exon skipping and out-of-frame fusion of exons 3 and 5, causing altered STAT3 phosphorylation in IL10-induced peripheral blood mononuclear cells. The patient developed colitis at 6 years of age, the oldest reported age of onset among patients with IL10RA mutations, and did not suffer from perianal disease. We report three paediatric patients with a rare, synonymous p.T179T variant causing a splicing error in IL10RA.

Malnutrition and growth retardation are important issues in treating pediatric Crohn's disease (CD). Thus, we aimed to investigate the prevalence of various nutritional and growth parameters at the time of diagnosis in Korean children with CD. Seventy-one children (<18 years) were enrolled. We analyzed the Z-scores of height-for-age (HAZ), weight-for-height (WHZ), body mass index for age (BMIZ), bone mineral density for age (BMDZ), and the biochemical markers measured at the time of diagnosis. At diagnosis, HAZ <-2 was observed in three patients (4%), WHZ <-2 in 20 patients (28%), BMIZ <-2 in 19 patients (27%), and BMDZ <-2 in 11 patients (18%). The HAZ was significantly lower in females and patients with extraintestinal manifestations, and the WHZ and BMIZ were significantly lower in patients with stricturing and penetrating disease. Subnormal serum levels were highly prevalent for hemoglobin, albumin, iron, ferritin, calcium, magnesium, folate, vitamin B12, and zinc. There was a significant correlation between nutritional status, growth retardation, and disease activity. Abnormal nutritional status was highly prevalent in Korean children with CD at the time of diagnosis and was associated with the extent, behavior, and activity of the disease.