Helicoid peripapillary chorioretinal degeneration in abetalipoproteinemia.

Abetalipoproteinemia is a rare autosoma1 recessive disorder characterized by the absence of apolipoprotein B.' It is caused by mutations of the microsomal triglyceridetransfer protein gene.' Ocular manifestations include retinitis pigmentosa-like changes, nystagmus, ophthalmoplegia, ptosis, cataracts, anisocoria, and angioid ~treaks.~ Helicoid peripapillary chorioretinal degeneration (HPCD) is characterized by chorioretinal atrophy that radiates from the optic disc as winglike extension^.^ No systemic disease has been associated with HPCD. We report a case of HPCD associated with abetalipoproteinemia. Report of a Case. A 24-year-old woman had been diagnosed with abetalipoproteinemia at age 2 years. The diagnosis was based on peripheral blood acanthocytosis, low serum cholesterol levels, absence of serum lipoprotein, and characteristic lipid deposits in mucosal cells on small bowel biopsy. She was treated with vitamin E injection and oral vitamins A, D, and K. Results of initial ocular examinations were within normal limits. At age 18 years, the patient voluntarily discontinued treatment with vitamin supplementation; afterward she reported worsening of night vision and progressive field changes. She was evaluated at the Ocular Genetics Clinic of The Hospital for Sick Children, Toronto, bn ta r io , at age 24 years. Bestcorrected vision was 20/20 OU. Refraction was -0.75+0.50X 165" OD and -1.00+1.00X 175" 0s. O~hthalmoscopy showed bilateral and symmetric helicoid peripapillary changes (Figure 1 ), equatorial retinal pigment epithelium (RPE) mottling, and attenuation of blood vessels but absence of true angioid streaks. There was no sign of inflammation. " Fluorescein angiography showed a large peripapillary defect with no evidence of leakage or angioid streaks (Figure 2) . A Goldmann visual field examination revealed bilateral constriction of the peripheral field and enlargement of the blind spot. Electroretinogram recordings were severely attenuated to all stimuli. The serum level of vitamin A was 0.20 pmol/L (normal range, 1.05-3.14 pmoVL), whereas for vitamin E, it was 7.0 pmoVL (normal range, 12.0-46.0 pmoVL). Vitamin therapy was restarted, and 6 months into treatment there was no progression of symptoms.