Pseudohomozygous type II hyperlipoproteinemia.

A 12-month-old boy with clinical findings suggestive of homozygous familial hypercholesterolemia, who had no secondary causes of hypercholesterolemia, and whose parents had no lipid abnormalities, was reported. No abnormalities were noted in the low density lipoprotein (LDL) receptor activities of the fibroblasts from patient, parents and sibling.