Familial hypobetalipoproteinemia: early neurological, hematological, and ocular manifestations in two affected twins responding to vitamin supplementation

Familial hypobetalipoproteinemia is a disorder of lipid metabolism characterized by extremely low plasma levels of apolipoprotein B as well as low levels of total and low-density lipoprotein cholesterol. We report the case of impairment of retinal function and diffuse pain in both legs often related to physical activity, as well as the presence of acanthocytosis on peripheral blood smear. Neurophysiological studies suggested dysfunction of the thin myelinated (A) and unmyelinated (C) fibers, in spite of preserved A fiber function, which has not been previously described in this condition. All clinical symptoms and the neurophysiological abnormalities improved after high-dose vitamin E and A supplementation. These findings suggest that this syndrome may have a wide spectrum of manifestations and an early appearance of symptoms in the pediatric age group.