PATHOLOGY OF HEREDITARY RETINAL DEGENERATION ASSOCIATED WITH HYPOBETALIPOPROTEINEMIA

Background: The clinical features and previously unreported ocular pat hology in a case of heterozygous hypobetalipoproteinemia (HBL) associa ted with a pigment epitheliopathy are documented. Night blindness deve loped in a white woman with familiar heterozygous HBL (cholesterol and low-density lipoprotein levels < 5% of normal) at 51 years of age. Op hthalmoscopy showed bilateral symmetric depigmentation at the posterio r pole with pigment clumping and pavingstone configuration in the peri phery. By the time the patient died, at 75 years of age, vision had de teriorated to hand motions. Methods: One eye was removed 2 hours postm ortem for light and electron microscopic study. Results: The photorece ptors were absent, and the outer nuclear layer was replaced by glial c ells throughout most of the retina, but there was some focal photorece ptor preservation in isolated regions. The outstanding feature was a m assive deposition of basal linear deposit which was calcified in segme nts and which contained macrophages and the processes of glial cells: trilaminar bodies and melanin granules were identified in the macropha ges. The remaining retinal pigment epithelial cells contained melanin but very little lipofuscin: intraretinal migration was minimal. Conclu sion: The authors postulate that the pigment epitheliopathy associated with HBL is an abiotrophy in which photoreceptor discs are unable to regenerate due to locally disordered metabolism resulting from or acti ng in concert with the pigment epitheliopathy.