A parent-of-origin effect on atherosclerosis susceptibility was evident in the study by Breslow and colleagues [26], in which the authors observed striking differences in LOD scores for QTL peaks on Chr3 and Chr12 when B6-Ldlr-null males were mated with FVB-Ldrl-null females versus when FVB- Ldrl-null males were mated with B6-Ldrl-null females. This evidence concerns the gene LDLR and atherosclerosis.