The intense search which has developed around understanding the pathological mechanisms of atherosclerosis has underlined the complexity of a process which involves very many proteins, the products of genetic information. This observation, combined with genetic epidemiological data, has introduced the notion of familial susceptibility applicable to atherogenic dyslipidaemia. This susceptibility relies on the presence of mutations, more or less frequent in the population, affecting the key genes in plasmatic lipid transport. The mutations which are currently the best documented concern the genes involved in the metabolism of atherogenic lipoproteins: LDL-receptor, apo B or apo E. Nevertheless, a better understanding of the inverse transport of cholesterol would allow progressive demonstration of the mutations affecting HDL metabolism. The aim of such work encompasses the characterisation of the most relevant mutations for defining coronary risk, and a better understanding of the interactions of these mutations with conventional environmental risk factors.