AIM: Chromodomain helicase DNA-binding protein 5 (CHD5) plays a role in normal 
neural development and in tumorigenesis of various human cancers. However, its 
role in primary gallbladder carcinoma (PGC) is still unclear. The aim of this 
study was to investigate CHD5 expression in PGC and its clinical significance.
METHODS: CHD5 mRNA and protein expression in 120 PGC and 20 normal gallbladder 
specimens was determined by quantitative reverse transcription-polymerase chain 
reaction (QRT-PCR) and Western blotting analysis, respectively.
RESULTS: The expression levels of CHD5 mRNA and protein in PGC tissues were both 
significantly lower than those in the normal epithelium of the gallbladder 
(mRNA: P = 0.006; protein: P = 0.01). CHD5 mRNA expression was closely 
correlated with its protein expression (r = 0.8; P < 0.001). Additionally, the 
low expression of CHD5 protein was significantly associated with high pathologic 
T stage (P = 0.01) and clinical stage (P = 0.008), and advanced histologic grade 
(P = 0.009). The expression levels of CHD5 protein in PGC tissues with positive 
nodal metastasis were also significantly lower than those without (P = 0.01). 
Survival analysis showed that low CHD5 expression was associated with shorter 
disease-free (P = 0.01) and overall survival (P = 0.008) compared to those with 
high CHD5 expression in PGC patients. Furthermore, multivariate analyses showed 
that the decreased expression of CHD5 was an independent prognostic marker for 
both unfavorable disease-free (P = 0.01) and overall survival (P = 0.006).
CONCLUSION: CHD5 may be involved in carcinogenesis of PGC and its 
down-regulation may be significantly correlated with unfavorable 
clinicopathologic features including poor overall and disease-free survival in 
patients.