The apo genes clustered at 11q23.3 chromosomal region codes for plasma apolipoproteins APOA1, APOC3, APOA4 and APOA5. APOA1, as a major component of HDL and cofactor for lecthin cholesterol acyl transferase (LCAT) enzyme, is an established biochemical marker of CAD. The gene discussed is LCAT; the disease is coronary artery disorder.