The metabolism of low-density lipoprotein in a patient with familial hyperbetalipoproteinaemia.

1. Plasma low-density lipoprotein (LDL) from a patient with homozygous familial hyperbetalipoproteinaemia was labelled with '1 and LDL from a matched normal subject was labelled with 1311. The two samples of LDL were injected simultaneously into the patient and into a second normal subject. 2. In each subject the fractional rate of turnover of the two LDL samples was the same, but the fractional rate in the patient was less than half that in thenormal subject. 3. It is concluded that the hyperbetalipoproteinaemia in the patient was not due to an abnormality in her LDL protein recognizable by her own body or by that of the normal recipient.