Alpha 1 antitrypsin gene: A case-control study in chronic obstructive pulmonary disease

Alpha-1 antitrypsin (AAT) deficiency is an inherited disorder that causes low levels of, or no AAT in the blood. The most common illness in adults with AAT deficiency is lung disease during the third and fourth decades of life. Most commonly, it is associated with chronic obstructive pulmonary disease (COPD). Mutations in the protease inhibitor (PI) gene, located on chromosome 14, are associated with this genetic disorder. The Z protein is due to a single amino acid substitution of 342 glutamine lysine. Although cigarette smoking is the main environmental risk factor, only about 15% of smokers develop clinically significant disease suggesting other influences on disease expression. The study included hospital based age and sex matched 100 cases of COPD and 100 controls without COPD recruited from Christian Medical Centre, Jorhat, Assam. These cases were recruited from February 2009 to December 2009. Subjects were included in the COPD group on the basis of lung function test. DNA extraction was done by DNA extraction kit and amplification for AAT gene was done by site directed mutagenesis polymerase chain reaction (PCR) method as described by Tazellar et al. (1992). We found that smoking was the prior cause of COPD. A1AT deficiency is not prevalent in our population subset but certain other genes could be the attributable factor for COPD.