On the relationship between Lp(a) Iipoprotein, “sinking pre‐β‐lipoprotein” and inherited hyper‐β‐lipoproteinaemia

The presence of extra pre‐β‐lipoprotein bands on lipoprotein electrophoretograms has recently been implicated by different workers as a major risk factor in coronary heart disease. We observed such “sinking pre‐β‐lipoprotein” in members of three kindreds which were being studied because of hyper‐β‐lipoproteinaemia with xanthomatosis and coronary heart disease (type IIa hyperlipoproteinaemia). The hyper‐β‐lipoproteinaemia, Lp(a) antigen and extra lipoprotein band segregated in an autosomal dominant fashion in these families. Electrophoretic and immunologic studies confirmed the identity of “sinking pre‐β‐lipoprotein” with the Lp(a) lipoprotein. Presence of “sinking pre‐β‐lipoprotein” reflects high concentration of the Lp(a) lipoprotein. Close genetic linkage between hyper‐β‐lipoproteinaemia and the Lp trait was excluded. Thus, the present data speak against linkage as well as association between hyper‐β‐lipoproteinaemia as it occurs in the three kindreds and the Lp trait. If the possilble association of Lp(d) lipoprotein with coronary heart diease, as suggested by studies of other workers, is confirmed, the data from the present family study may suggest that the majority of cases of coronary heart disease are genetically distinct from hyper‐β‐lipoproteinaemia of type IIa.