Objective: To analyze the association of the polymorphism of Met764Thr with bronchial asthma and lung function of asthmatic subjects of Han nationality in Southern China.
Methods: In 164 unrelated patients with asthma and 112 unrelated healthy controls, polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and DNA sequencing were used to determine polymorphism of Met764Thr locus allele in ADAM33 gene. The clinical indexes associated with lung function (FVC%, FEV(1)%) were compared among the three genotypes (Met764/Met764, Met764/Thr764, Thr764/Thr764) in asthmatic subjects.
Results: No significant difference was found in the allele (Met764, Thr 764) frequency among populations in UK, US, German, Korean, and Southern China (chi(2) = 6.77, P > 0.05). The frequencies of the genotypes (Met764/Met764, Met764/Thr764, Thr764/Thr764) were respectively 78.7% (129), 18.3% (30), 3.0% (5) in 164 asthmatic subjects and respectively 91.1% (102), 6.3% (7), 2.7% (3) in the 112 controls. There was a significant difference in the distributions of the genotypes (Met764/Met764, Met764/Thr764, Thr764/Thr764) between asthmatic subjects and controls (chi(2) = 8.46, P < 0.05). The frequencies of alleles (Thr764) were respectively 12.2% in the asthmatic subjects and 5.8% in the controls. Significant difference was observed in the allele (Met764, Thr 764) frequency between the two groups (chi(2) = 6.27, P < 0.05). The presence of Thr764 allele of ADAM33 gene was found to be a greater risk factor in asthmatic subjects than in controls. The odds ratio (OR) of Met764/Thr764 and Met764/Thr764 + Thr764/Thr764 were 3.389 (1.430 - 8.030), 2.767 (1.308 - 5.854), respectively. When compared with Met764/Met764 genotype, all P < 0.05. There was a significant decrease in the FVC% and FEV(1)% levels of Met764/Thr764, Thr764/Thr764 and Met764/Met764 genotype.
Conclusions: These results suggest that Met764Thr locus genetic polymorphism is associated with susceptibility of asthma and clinical indexes of lung function of asthmatic subjects of Han nationality in Southern China.