Bassen-Kornzweig syndrome
| Abetalipoproteinemia | |
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| Synonyms | Bassen-Kornzweig syndrome |
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| Micrograph showing enterocytes with a clear cytoplasm (due to lipid accumulation) characteristic of abetalipoproteinemia. Duodenal biopsy. H&E stain. | |
| Specialty |
Endocrinology 
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| Classification | |
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| External resources |
Abetalipoproteinemia is a disorder that interferes with the normal absorption of fat and fat-soluble vitamins from food. It is caused by a mutation in microsomal triglyceride transfer protein resulting in deficiencies in the apolipoproteins B-48 and B-100, which are used in the synthesis and exportation of chylomicrons and VLDL respectively. It is not to be confused with familial dysbetalipoproteinemia.
It is a rare autosomal recessive disorder.
Often symptoms will arise that indicate the body is not absorbing or making the lipoproteins that it needs. These symptoms usually appear en masse, meaning that they happen all together, all the time. These symptoms come as follows:
Abetalipoproteinemia affects the absorption of dietary fats, cholesterol, and certain vitamins. People affected by this disorder are not able to make certain lipoproteins, which are molecules that consist of proteins combined with cholesterol and particular fats called triglycerides. This leads to a multiple vitamin deficiency, affecting the fat-soluble vitamin A, vitamin D, , and vitamin K. However, many of the observed effects are due to vitamin E deficiency in particular.
The signs and symptoms of abetalipoproteinemia appear in the first few months of life (because pancreatic lipase is not active in this period). They can include failure to gain weight and grow at the expected rate (failure to thrive); diarrhea; abnormal spiny red blood cells (acanthocytosis); and fatty, foul-smelling stools (steatorrhea). The stool may contain large chunks of fat and/or blood. Other features of this disorder may develop later in childhood and often impair the function of the nervous system. They can include poor muscle coordination, difficulty with balance and movement (ataxia), and progressive degeneration of the retina (the light-sensitive layer in the posterior eye) that can progress to near-blindness (due to deficiency of vitamin A, retinol). Adults in their thirties or forties may have increasing difficulty with balance and walking. Many of the signs and symptoms of abetalipoproteinemia result from a severe vitamin deficiency, especially vitamin E deficiency, which typically results in eye problems with degeneration of the spinocerebellar and dorsal column tracts.
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