title: Eosinophilic gastroenteritis in a patient with Bruton's tyrosine kinase deficiency.
abstract: Eosinophilic gastrointestinal diseases (EGID) are relatively rare diseases characterized by eosinophilic infiltration of the gastrointestinal tract resulting in various gastrointestinal symptoms. EGID are often caused by allergic reactions or systemic eosinophilic disorders, but their comorbidity with Bruton's tyrosine kinase (BTK) deficiency has not been previously documented. Here, we report a case of eosinophilic gastroenteritis (EG) in a patient with BTK deficiency. Despite adequate replacement immunoglobulin (Ig) therapy, trough serum IgG was not maintained. To identify the underlying cause of the low trough level and chronic diarrhea, the intestine was investigated on endoscopy. We also screened for the variable number of tandem repeat polymorphism in FCGRT. Genetic analysis could not explain the low trough IgG, but endoscopy indicated eosinophilic enterocolitis. EG may be an important differential diagnosis when primary immunodeficiency patients have chronic diarrhea or continued low serum IgG.
authors: Department of Pediatrics and Adolescent Medicine, Juntendo University Graduate School of Medicine, Tokyo, Japan.
authors: Susumu
authors: S
authors: Yamazaki
authors: Department of Pediatrics and Adolescent Medicine, Juntendo University Graduate School of Medicine, Tokyo, Japan.
authors: Yoshikazu
authors: Y
authors: Ohtsuka
authors: Department of Pediatrics and Adolescent Medicine, Juntendo University Graduate School of Medicine, Tokyo, Japan.
authors: Tomoaki
authors: T
authors: Yokokura
authors: Department of Pediatrics and Adolescent Medicine, Juntendo University Graduate School of Medicine, Tokyo, Japan.
authors: Rena
authors: R
authors: Yokota
authors: Department of Pediatrics and Adolescent Medicine, Juntendo University Graduate School of Medicine, Tokyo, Japan.
authors: Asuka
authors: A
authors: Honjo
authors: Department of Pediatrics and Adolescent Medicine, Juntendo University Graduate School of Medicine, Tokyo, Japan.
authors: Eisuke
authors: E
authors: Inage
authors: Department of Pediatrics and Adolescent Medicine, Juntendo University Graduate School of Medicine, Tokyo, Japan.
authors: Yosuke
authors: Y
authors: Baba
authors: Department of Pediatrics and Adolescent Medicine, Juntendo University Graduate School of Medicine, Tokyo, Japan.
authors: Mari
authors: M
authors: Mori
authors: Department of Pediatrics and Adolescent Medicine, Juntendo University Graduate School of Medicine, Tokyo, Japan.
authors: Ryuyo
authors: R
authors: Suzuki
authors: Pediatric Science, Department of Child Health and Development, Faculty of Home Economics, Tokyo Kasei University, Tokyo, Japan.
authors: Tsutomu
authors: T
authors: Iwata
authors: Department of Pediatrics and Adolescent Medicine, Juntendo University Graduate School of Medicine, Tokyo, Japan.
authors: Toshiaki
authors: T
authors: Shimizu
keywords: Bruton's agammaglobulinemia; FCGRT; X-linked agammaglobulinemia; gastroenteritis; neonatal Fc receptor (FcRn)