Certain rare protein-truncating variants (PTVs) in two cholesterol-related genes are associated with a substantial reduction in the risk of coronary heart disease (CHD), according to a study appearing this week in JAMA Cardiology. There is a well-established linked between low-density lipoprotein concentrations and PTVs in the apolipoprotein B (APOB) and proprotein convertase subtilisin/kexin type 9 (PCSK9) genes, which are involved in LDL production and metabolism, respectively. However, the effect of these variants on CHD remains unclear. To investigate, a team led by scientists from Massachusetts General Hospital analyzed genetic data on over 200,000 individuals from the US and UK. They find that .4 percent of the people included in the study carried either an APOB or PCSK9 PTV and that these variants were associated not only with lower LDL levels, but as much as a 49 percent lower risk of CHD as well. "This inherited reduction in LDL cholesterol provides additional evidence to support recommendations to maintain low LDL cholesterol levels as early as possible, as lifetime cumulative exposure is a primary driver of risk for CHD," the study's authors write.