Related Disorders List

Information on the following diseases can be found in the Related Disorders section of this report:

• Tangier Disease (Alphalipoproteinemia)

Symptoms

Symptoms of Acanthocytosis usually begin during the first year of life. They may include:

DIGESTIVE Digestive tract symptoms may include poor appetite, vomiting, loose voluminous stools, and diminished absorption of nutrients from food. The fat content of the intestinal mucous membrane cells tends to be very high. Although patients with this disorder do not metabolize these fats well, only 15 to 20% of the ingested fat is excreted in the stool. Fat-soluble vitamins such as vitamins A, E, and K are also poorly absorbed. The resulting vitamin K deficiency causes blood clotting factor levels to diminish.

NEUROMUSCULAR Infants with Acanthocytosis usually grow slowly. They may lose stretch reflexes. At least one third of affected children have neuromuscular problems during the first decade of life. Poor muscle coordination (ataxia) usually develops before age 20. Only a few patients with Acanthocytosis are able to stand unassisted by their fourth decade of life because spinocerebellar degeneration causes loss of position and vibratory sensation. (For more information, choose "ataxia" as your search term in the Rare Disease Database.) Loss of the fatty layer around some nerve cells (demyelination) in the posterior spinal column may also occur. Some loss of pain, temperature and touch sensations may also develop. Mental retardation occurs in about one third of patients. Weakness and muscle wasting (atrophy) may occur, and in rare cases, heart problems may develop.

SKELETAL Backward curvature (lordosis) or backward and sideways curvature of the spine (kyphoscoliosis), a highly arched foot (pes cavus) or clubfoot may occur in people affected with this disorder. These skeletal abnormalities probably result from muscle imbalances during crucial stages of bone development.

OCULAR Night blindness with rapidly progressing retinal disease (Retinitis Pigmentosa, also known as RP) are other symptoms of Acanthocytosis. Retinitis Pigmentosa usually starts at about 10 years of age. Loss of clear vision may begin sometime between the ages of 7 and 30 years, and can progress to blindness. Involuntary rapid movement of the eye (nystagmus) is common in this disorder. Paralysis of the eye muscles (ophthalmoplegia) may also occur. (For more information on this disorder, choose "RP" as your search term in the Rare Disease Database.)

BLOOD - LYMPH Abnormal red blood cells (acanthocytes) are present in this disorder. Plasma cholesterol in the blood falls to a very low level. Low-density betalipoproteins are absent or severely deficient in blood plasma. There is lack of formation of fat-containing droplets in the lymph vessels (chilomicrons) after eating fats.

Causes

Acanthocytosis is a hereditary disorder caused by autosomal recessive genes. In many cases this disorder is found when parents of patients with Acanthocytosis are blood relatives. Doubling of the mutant gene probably occurs in these cases. Human traits including the classic genetic diseases, are the product of the interaction of two genes for that condition, one received from the father and one from the mother. In recessive disorders, the condition does not appear unless a person inherits the same defective gene for the same trait from each parent. If an individual receives one normal gene and one gene for the disease, the person will be a carrier for the disease, but usually will not show symptoms. The risk of transmitting the disease to the children of a couple, both of whom are carriers for a recessive disorder, is 25 percent. Fifty percent of their children risk being carriers of the disease, but generally will not show symptoms of the disorder. Twenty-five percent of their children may receive both normal genes, one from each parent, and will be genetically normal (for that particular trait). The risk is the same for each pregnancy.

Affected Populations

Acanthocytosis is a very rare disorder. Symptoms usually first appear during the first year of life. Males and females are affected in equal numbers.

Related Disorders

Symptoms of the following disorder can be similar to those of Acanthocytosis. Comparisons may be useful for a differential diagnosis:

Tangier Disease (Alphalipoproteinemia) is an inherited blood disorder characterized by decreased concentrations of fat compounds in the blood called high density lipoproteins. Large amounts of these compounds may accumulate in certain organs of the body causing tissue discoloration. In later stages, these accumulations may cause liver and spleen enlargement and/or neurological problems. (For more information on this disorder, choose "Tangier" as your search term in the Rare Disease Database.)

Standard Therapies

Dietary restriction of long chain fatty acid triglycerides may relieve gastrointestinal symptoms. Large doses of Vitamin E prescribed under a doctor's supervision may improve the muscle symptoms of Acanthocytosis and can prevent retinal disease (retinopathy) in some patients affected with this disorder. However, Vitamin E does not stop progression of the disease. Other treatment is symptomatic and supportive. Social service agencies may be helpful for mentally retarded and/or blind children and their families. Genetic counseling is recommended for families of children with Acanthocytosis.

References

McKusick VA., ed. On-Line Mendelian Inheritance in Man (OMIM). Baltimore, MD: The Johns Hopkins University; Entry No; 200100: Created; 6/2/86: Most recent update; 11/4/98.

TEXTBOOKS
Kane JP, Havel RJ. Disorders of the biogenesis and secretions of lipoproteins containing the B apolipoproteins. In: Scriber CR, et al., eds. The Metabolic and Molecular Basis of Inherited Disease, 7th ed. New York, NY: McGraw-Hill Company; 1995:1853-85.

Palek J, Jarolim P., Red cell membrane disorders. In: Hoffman R, et al., eds. Hematology. 2nd ed. New York, NY: Churchill Livingstone Inc; 1995:690-694.

REVIEW ARTICLES
Veniant MM, et al., Insights into apolipoprotein B biology from transgenic and gene-targeted mice. J Nutr. 1999;129(2S Suppl):451S-55S.

Lonardo A, et al., Familial heterozygous hypobetalipoproteinemia, extrahepatic primary malignancy, and hepatocellular carcinoma. Dig Dis Sci. 1998;43:2489-92.

Ohashi K, et al., A truncated species of apolipoprotein B (B-38.7) in a patient with homozygous hypobetalipoproteinemia associated with diabetes mellitus. Arterioscler Thromb Vasc Biol. 1998;18:1330-34.

JOURNAL ARTICLES
Wu J, et al., Known mutations of apoB account for only a small minority of hypobetalipoproteinemia. J Lipid Res. 1999;40:955-59.

Welty FK, et al., Frequency of apoB and apoE gene mutations as causes of hypobetalipoproteinemia in the framingham offspring population. Arterioscler Thromb Vasc Biol. 1998;18:1745-51.

Pulai JI, et al., Genetic heterogeneity in familial hypobetalipoproteinemia: linkage and non-linkage to the apoB gene in Caucasian families. Am J Med Genet.

Castellano G, et al., Diffuse fatty liver in familial heterozygous hypobetalipoproteinemia. J Clin Gastroenterol. 1997;25:379-82.

Tarugi P, et al., Heterozygous familial hypobetalipoproteinemia associated with fatty liver. Am J Gastroenterol. 1997;92:1400-02.