Pediatric Crohn disease: Clinical and genetic characteristics in Taiwan

Objectives: Crohn disease (CD) is a heterogeneous disorder. The nucleotide oligomerization domain 2/caspase activating recruitment domain 15 (NOD2/CARD15) gene located at 16q12 is strongly associated with susceptibility to CD in white people but is absent in adult Asian patients, whereas the role of Toll-like receptor 4 (TLR4) polymorphisms has also been reported. Because clinical and genetic data in Asian children with CD are lacking, the aim of this study was to elucidate the clinical and genetic characteristics of Taiwanese children with CD. Patients and Methods: All of the children hospitalized at the National Taiwan University Hospital between January 2000 and July 2005 who fulfilled the diagnostic criteria for CD were enrolled. Their clinical characteristics were recorded, and genomic DNA was extracted from their white blood cells. After polymerase chain reaction was performed, direct sequencing was done to detect the 4 NOD2 hotspot mutations (P268S, R702W, G908R, 1007fs) and TLR4 polymorphisms (Asp299Gly, Thr399Ile). Results: CD was diagnosed in 10 children (6 boys and 4 girls; age range at diagnosis, 14 months to 13 years; median age, 11.1 years). There were 5 children with ileocolonic region involvement, 3 with colonic region involvement, 2 with ileal region involvement, 4 with additional upper gastrointestinal tract involvement, and 2 with additional perianal fistula. Half of the children had growth retardation at diagnosis. Neither NOD2/ CARD 15 mutations nor TLR4 polymorphisms were found in the 10 patients. Conclusions: Ileocolonic location and inflammatory behavior constitute the most frequent phenotype of CD in Taiwan. Mutations in the NOD2/CARD15 and TLR4 genes that are common in the West are not associated with CD in Taiwanese children.