Abetalipoproteinemia

Clinical Characteristics

Ocular Features:

The major ocular manifestations of abetalipoproteinemia are in the retina which develops diffuse and sometimes patchy pigmentary changes often called atypical retinitis pigmentosa. In other cases the picture resembles retinitis punctata albescens with perivascular white spots in the peripheral retina. Night blindness is an early and prominent symptom with abnormal dark adaptation thresholds evident before fundus pigment changes are seen. The ERG shows loss of rod function before that of cone function. The macula may or may not be affected while peripheral fields are often severely constricted. Loss of photoreceptors occurs throughout life and visual fields show progressive constriction, sometimes with central sparing. A single case of bilateral disc swelling in a 9 year-old girl has been reported.

Systemic Features:

Celiac disease and steatorrhea due to a deficiency of circulating chylomicra underlie the malabsorption of vitamins A and E which is probably responsible for the majority of systemic manifestations. Red blood cells have a peculiar burr-like morphology that has led to the designation 'acanthocytes'. Liver failure and cirrhosis sometimes occur. Plasma lipids are generally low including cholesterol, triglycerides, and beta lipoproteins. Central and peripheral nerve demyelination occurs leading to a progressive ataxia and other neurological symptoms.

Genetics

This autosomal recessive disease seems to result from an inability to synthesize the apoB peptide that is a part of the LDL and VLDL. A mutation in the MTP [1] gene (4q22-q24) is responsible. The gene is sometimes called MTTP [2] as it codes for micosomal triglyceride transfer protein.

Acanthocytosis is also a feature in the autosomal recessive condition known as chorea-acanthocytosis (200150 [3]), a progressive degenerative movement disorder primarily affecting the limbs resulting from mutations in the VPS13A gene.

Treatment

Treatment Options:

Treatment with vitamins A and E may be beneficial. Cone function improves before rod function with massive doses of vitamin A but usually only after months of treatment. It has been reported that Vitamin A alone without vitamin E is insufficient to arrest the retinal disease.

References

Article Title:

Disc swelling in abetalipoproteinemia: a novel feature of Bassen-Kornzweig syndrome [4]

Nasr MB, Symeonidis C, Mikropoulos DG, Kozeis N, Tsinopoulos I, Dimitrakos SA, Konstas AG. Disc swelling in abetalipoproteinemia: a novel feature of Bassen-Kornzweig syndrome. Eur J Ophthalmol. 2011 Sep-Oct;21(5):674-6.

PubMed ID:

21484752

Oral vitamin E supplements can prevent the retinopathy of abetalipoproteinaemia [5]

Runge P, Muller DP, McAllister J, Calver D, Lloyd JK, Taylor D. Oral vitamin E supplements can prevent the retinopathy of abetalipoproteinaemia. Br J Ophthalmol. 1986 Mar;70(3):166-73.

PubMed ID:

3954973

Retinitis pigmentosa in abetalipoproteinemia: Effects of vitamin A [6]

Gouras P, Carr RE, Gunkel RD. Retinitis pigmentosa in abetalipoproteinemia: Effects of vitamin A. Invest Ophthalmol. 1971 Oct;10(10):784-93.

PubMed ID:

5124019