The goal of this observational study is to investigate the associations between tumor necrosis factor superfamily member 4 (TNFSF4) gene polymorphisms and the risk of Crohn's disease (CD), and to elucidate the impact of TNFSF4 gene variations on the CD clinical phenotype and the efficacy of ustekinumab (UST). The main question it aims to answer is: Does TNFSF4 polymorphism affect susceptibility to CD and the efficacy of UST in CD patients? Participants will have their blood drawn upon enrollment

From January 2018 to May 2025, a total of 296 CD patients and 532 gender- and age-matched normal controls were collected from the Department of Gastroenterology, the Second Affiliated Hospital of Wenzhou Medical University.The genotypes of TNFSF4 were determined by multiplex polymerase chain reaction-ligase detection reaction technique. Unconditional logistic regression was employed to analyze the distribution of TNFSF4 gene polymorphisms between CD group and normal control group, as well as their influences on the clinicopathological characteristics of CD patients. Unconditional logistic regression model was used to explore the effect of TNFSF4 gene variation on the clinical response of CD patients in the treatment of UST at week 8 and mucosal healing at week 34, respectively.

Inclusion Criteria:

• diagnosed CD based on comprehensive clinical, colonoscopy, histopathological, laboratory, and radiographic examination results

Exclusion Criteria:

• rheumatoid arthritis, systemic lupus erythematosus, intestinal tuberculosis, ischemic enteritis, radiation enteritis, tumors, etc.

There was no statistically significant difference in the gender ratio, average age, and proportion of smokers between CD group and normal control group. All study subjects are from the Zhejiang Han population who are not related by blood.