Of the lipids that we typically check for LDL is the strongest prector of risk. HDL when high takes away one of the conventional risk factots for CAD but we don't know what it means when it's low. There is some evidnece to suggest that low HDL in isolation does increase the risk. The final word on this topic isn't out yet. In your situation, the family history is the strogest predictor of risk. You should therefore try to limit any known risk factor to the minimum. I would therefore treat your low HDL, at least with diet and exercise at first and maybe even with fish oil or even niacin. These are relatively simple medicaitons. You should also probably see a specialist who could look into the newer tests such as CRP or LPa which may be affected by genetics (family Hx).