Hyperlipidaemic xanthomatosis. II. Mode of inheritance in 55 families with essential hyperlipidaemia and xanthomatosis.

Xanthomata of the skin were first described in the English literature by Addison and Gull in 1851, and their hereditary nature was indicated by Hutchinson in 1871. Pick and Pinkus in 1909 (quoted by Harlan, Graham, and Estes, 1966) first described their association with raised plasma lipids. Familial hyperlipidaemia is not uncommon, but in spite of the relatively large number of reported pedigrees the mode of inheritance of the phenotypes is still uncertain. The heterogeneity of the metabolic disorders associated with familial hyperlipidaemia has been one source of confusion. Recently, Fredrickson and Lees (1965, 1966) have dis- tinguished at least five distinct varieties of hyperlipidaemia on the basis of the lipoprotein pattern, and there is a suggestion that others may emerge. Many previous studies of the inheritance of this condition are based solely on the level of serum cholesterol values in the family, thus failing to differentiate between individual varieties of hyperlipidaemia. Furthermore, there has been under- standable difficulty in establishing the best criteria to discriminate between 'affected' and 'normal' indi- viduals within families.