ABSENCE OF THE B-100 APOLIPOPROTEIN

A B S T R A C T In the two genetic forms of abetalipoproteinemia described previously, recessive abetalipoproteinemia and homozygous hypobetalipoproteinemia, all lipoproteins that normally contain apolipoprotein B are absent from plasma. We describe here a new disorder in which normal low density and very low density lipoproteins are absent, but in which triglycerides are absorbed from the intestine and chylomicrons are present in plasma. The underlying molecular defect appears to be selective deletion ofthe hepatogenous B-100 apolipoprotein. The B-48 apolipoprotein found in chylomicrons is spared. These findings suiggest that the two species of apolipoprotein B are uniider separate genetic control and that low density lipoproteins are not normally derived from chylomicronis.