Abetalipoproteinemia is a rare disorder presenting in infancy or early childhood and affecting less than 1 in 1 million. It is characterized by the malabsorption of fats and lipid soluble vitamins resulting in hypocholesterolemia and vitamin deficiency. This is mainly caused by the improper packaging and secretion of apolipoprotein B-containing proteins. The disease can result in a failure to thrive, steatorrhia, developmental delay, spastic ataxia, neuropathy, retinal degeneration and hepatic steatosis.
The disease is diagnosed based on serum levels of lipids and fat soluble vitamins, absence of chylomicrons and VLDL in the plasma, acanthocytosis in blood films and presence of steatorrhic stools. Genetic testing to uncover a mutation in the MTP gene can confirm the diagnosis of abetalipoproteinemia. Treatment involves dietary therapy with reduced fat intake along with supplementation of medium chain triglycerides (MCT) and high doses of fat soluble vitamins.
Abetalipoproteinemia has been shown to follow an autosomal recessive pattern of inheritance and is associated with mutations in the MTP (Microsomal triglyceride transfer protein) gene.
Rafique and Zia (2011) reported on a 5 month old Saudi male, born to healthy unrelated parents, presenting with chronic diarrhoea and failure to thrive. On examination he was found to be severely malnourished with his weight, height and head circumference being below the 5th centile. Other observations included steatorrhic stools, a mildly distended abdomen and brittle, sparse and hypopigmented hair. Blood tests revealed very low levels of cholesterol, triglycerides and LDL. VLDL and chylomicrons were not detected. Acanthocytosis was evident in blood smears. Stool investigations uncovered several fat globules, occult blood traces and absence of reducing substances. A biopsy of the jejunal mucosa revealed multiple fat globules and the epithelial cells were found to be lacking in MTP protein. Genetic testing presented a homozygous 481 kb contiguous deletion between markers RH 8338 and RH 59351 affecting MTP and six other genes. Patient was diagnosed with abetalipoproteinemia and treated with MCT formula and fat soluble vitamins at high doses.