ABSTRACT
By now it will have become obvious that hypercholesterolaemia, however it is defined, is common (see Chapter 3) and that, though heterozygous familial hypercholesterolaemia (FH) is an important cause of marked hypercholesterolaemia, most hypercholesterolaemia is due to something else. If one considers the difference in serum cholesterol between nations where coronary heart disease (CHD) occurs frequently and those where it is infrequent, evidence that diet is a major cause of the commonly encountered hypercholesterolaemia is substantial (see Chapters 3 and 8). Nevertheless, not everybody consuming a Northern European or North American diet develops hypercholesterolaemia, and evidence that individual dietary preferences are closely related to the serum cholesterol concentration is poor.1 This
argues strongly that other factors must determine the individual response to diet. Such factors are frequently considered to be substantially genetic. The frequency distribution of the serum cholesterol concentration is reasonably gaussian, as it is, for example, for height. In the main, people at the top end of the cholesterol distribution are not there because of the influence of a single gene, as is the case for example in FH, but because of a combination of several genes interacting with environmental factors such as nutrition. This type of hypercholesterolaemia is usually referred to as polygenic hypercholesterolaemia.
