ObjectiveTo analyze the clinical characteristics of X-linked inhibitor of apoptosis (XIAP) deficient patients with clinical manifestation of Crohn's disease.

MethodsClinical manifestations, laboratory investigations, genetic testing and therapeutic interventions of one case of XIAP deficiency who was admitted to Department of Gastroenterology in Children's Hospital, Zhejiang University School of Medicine in May 2016 were summarized. PubMed and Chinese database for articles published from January 2016 to June 2017 were searched using the key words of'Crohn's disease’and'XIAP’, and the relevant literature was reviewed.

ResultsThe case we reported was a 6-year-1-month-old boy with recurrent bloody stool for 2 months, and abdominal pain with fever for 2 weeks. The patient had a past history of hemophagocytic lymphohistiocytosis (HLH) and epilepsy in the past one year. Complete blood cell count showed mild anemia (Hb108 g/L). The patient had an elevated high-sensitivity C reactive protein (86 mg/L) and erythrocyte sedimentation rate (46 mm/1h) . White blood cells, pus cells and red blood cells were found on routine stool examination. Biochemical panel showed hypoalbuminemia (25.2 g/L) , elevated transaminase (alanine aminotransferase 175 U/L, aspartate transaminase 229 U/L) , hypertriglyceridemia (4.41 mmol/L) , and hyperferritinemia (>1 650.0 μg/L) . Magnetic resonance enterography revealed the intestinal wall thickening and increased enhancement in parts of illeum and colon. Capsule endoscopy revealed multiple ulcers in jejunum. Colonoscopy showed multiple ulcers in colon and the pathological examination revealed chronic inflammation in mucosa of terminal ileum and colon, which was combined with partial necrosis and ulceration. Some phagocytes were seen in bone marrow smears. The patient was given multiple diagnoses, including hemophagocytic lymphohistiocytosis, Crohn's disease, sepsis, epilepsy, severe malnutrition, and hypoproteinemia. The pediatric Crohn's disease activity index (PCDAI) was 37.5. Genetic testing identified a hemizygotic mutation of c.910G>T chrX:123022501 p.G304X in XIAP. The parents had no such mutation. The patient showed response to infliximab with oral intake of mercaptopurine and corticosteroids, and had remission with PCDAI of 0. There were 9 relevant articles (Chinese 0 English 9), which showed 33.3% XIAP deficient patients manifested with inflammatory bowel disease(IBD), who might have other manifestations such as hemophagocytic lymphohistiocytosis or splenomegaly simultaneously or sequentially. Those patients showed poor response to monotherapy.

ConclusionXIAP deficient patients have various clinical manifestations. Genetic testing is important to those male pediatric IBD patients who have the complicated symptoms or little response to standard therapy.