Association of ADAM33 gene S1 and S2 transmembrane domain polymorphisms in COPD from South-Indian population
Background: Chronic obstructive pulmonary disease (COPD) is defined as a disease characterised by partially reversible and progressive airflow limitation associated with an abnormal inflammatory response of the lung with systemic manifestation. COPD is influenced by both environmental and genetic factors. ADAM33 (a disintegrin and metalloproteinase 33) has been one of the most exciting candidate genes for asthma and it was first associated with the disease in Caucasian populations. Recently, ADAM33 was shown to be associated with excessive decline of lung function and COPD. The aim of the study was to investigate the association of ADAM33 – S1 and S2 polymorphisms with COPD.
Subjects and methods: A total of 150 COPD patients attending the Department of Pulmonary Medicine, Government Chest Hospital, Erragadda, Hyderabad, India and 200 healthy control subjects were considered for the present study. A standard PCR–RFLP method was carried out for genotyping of ADAM33 S1-A/G and S2-C/G polymorphisms in all the participants.
Results: Genotypic distribution of the control and patient groups was compared with values predicted by the Hardy–Weinberg equilibrium, odds ratios (OR) and their respective 95% confidence intervals were used to measure the strength of association between ADAM33 S1 (A/G) and S2 (C/G) gene polymorphisms and COPD. The genotypic frequencies of ADAM33 gene S1 (A/G) polymorphism were found to be AA/AG/GG – 36%, 56%, 8% in controls and 5.33%, 10.66%, 84% in COPD cases, respectively. Genotypic frequencies for S2 (C/G) polymorphism were found to be CC/CG/GG – 14.47%, 78.20%, 5.92% in controls and 4%, 8% and 88% in COPD cases, respectively. There is a significant difference in distribution of genotypes and alleles of ADAM33 S1 and S2 gene polymorphisms between the two groups.
Conclusion: The present study suggests that the ADAM33 S1 and S2 gene promoter polymorphisms can be the major genetic predisposing factors in the aetiology of COPD.