Primary objective- To study the association of Lewis antigen and A, B, O blood group phenotypes with coronary artery disease patients attending the tertiary care hospital in Kerala.

The secondary objective-To find the association of Lewis antigen and A, B, O blood group phenotypes with smoking, alcohol use, diabetes, hypertension and dyslipidemia.

A case-control study to compare the prevalence of Lewis(a-b-) blood group among confirmed cardiac cases with the prevalence of the same among the general population and thereby find out if individuals with Lewis(a-b-) are more at risk of developing coronary artery disease. This may provide an economical and simple method for identifying subjects at increased risk for coronary artery disease and subsequently lead to more focused preventive measures and eventually to a specific treatment.

Inclusion Criteria:

- Patients in the age group of 30-55 years at the time of data collection diagnosed with coronary artery disease based on positive changes in coronary angiogram (more than 70% coronary stenosis)

Exclusion Criteria:

• Patients with other systemic illnesses like malignancy, autoimmune diseases.
• Patients who were not willing to participate in the study.

70 cases attending the Cardiology department who satisfy the inclusion and exclusion criteria were taken as cases.

140 (age and gender-matched) healthy blood donors who were eligible to donate blood as per the inclusion and exclusion criteria of Drugs and Cosmetics Rules, 1945 were taken as controls.