Objective      To explore the distribution of 389 CT (rs769217) polymorphism of catalase (CAT) gene in Han population of Chongqing

China

and the relationship between the polymorphism and noise-induced hearing loss (NIHL).       Methods      In Chongqing

China

427 unrelated a

dult Chinese Han people who were exposed to noise (noise exposure group) and 225 healthy volunteers without exposure (control group) were included in the study. The noise exposure group was further divided into NIHL (-) group (without NIHL

n=303) and NIHL (+) group (with NIHL

n=124). An improved multiplex ligation detection reaction (iMLDR) technique was employed to detect genotypes of 389 CT polymorphism of CAT gene. Allelic frequencies and clinical characteristics were compared among these groups.       Results      Three genotypes

CC

CT and TT

were detected. The frequencies of C and T allele of the CAT gene 389 CT polymorphism were 0.46 and 0.54 respectively. The genotype distribution in the control group and noise exposure group was in agreement with the Hardy-Weinberg equilibrium (

P

0.05). There was no significant difference in genotypic (CC

CT

TT) and allelic frequencies (C

T) between the control group and noise exposure group and between the control group and NIHL (-) group (

P

0.05). However

significant differences were observed between the control group and NIHL (+) group and between the NIHL (-) group and NIHL (+) group (

P

0.05)

especially in the case of dominant association effect (TT+CT vs CC

P

0.05).       Conclusion      The person who is exposed to noise with the T variant allele has significantly higher NIHL morbidity than those with homozygous C allele. CAT gene 389 CT polymorphism may be used as a biomarker for the assessment of NIHL morbidity in Chongqing Han population .