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PubMed1991

Intestinal and hepatic apolipoprotein B gene expression in abetalipoproteinemia.

A 20-year-old woman with abetalipoproteinemia underwent orthotopic liver transplantation for cirrhosis, affording access to her liver and small intestine for study. Before transplantation, her plasma apolipoprotein B concentration was less than 1 mg/dL according to enzyme-linked immunosorbent assay, whereas after transplantation her plasma apolipoprotein B concentration was 76 mg/dL (all apolipoprotein B-100). Apolipoprotein B content was reduced in her intestine and liver compared with normal and cirrhotic controls. Cultured hepatocytes from the patient's explanted liver secreted a 1.006 g/mL less than or equal to d less than or equal to 1.063 g/mL lipoprotein rich in apolipoprotein E and a 1.063 g/mL less than or equal to d less than or equal to 1.21 g/mL lipoprotein containing apolipoproteins E and A-I with no immunodetectable apolipoprotein B in the culture medium. Normal hepatocytes secreted very low-density lipoprotein and low-density lipoprotein containing apolipoprotein B-100. Abetalipoproteinemic intestinal apolipoprotein B messenger RNA concentration was 4-5-fold higher than control values. However, the patient's liver apolipoprotein B messenger RNA level was one fifth that of control normal and cirrhotic liver. Analysis of the patient's intestinal and hepatic apolipoprotein B messenger RNA for posttranscriptional stop-codon insertion revealed normally edited transcripts. These results suggest that apolipoprotein B is synthesized as the product of a normally edited messenger RNA transcript, but not secreted, in abetalipoproteinemia.

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PubMed1988

Neutral lipid transfer activities in the plasma of patients with abetalipoproteinemia.

Plasma lipid transfer proteins stimulate transfer and molecular exchange of cholesteryl esters, phospholipids and triglycerides between individual plasma lipoproteins. To assess whether transfer protein activities are influenced by the inherent absence of apo B-containing lipoproteins, we determined cholesteryl ester and triglyceride transfer activities in the plasma of patients with abetalipoproteinemia (ABL). Transfer activities were measured in plasma fractions of d greater than 1.21 g/ml in 2 patients with abetalipoproteinemia and 12 normal volunteers and were expressed as a percent transfer of labeled lipid from donor high density lipoproteins to acceptor very low density lipoproteins. Cholesteryl ester and triglyceride transfer activities were reduced respectively by 50% and 66% in the plasma of patients with ABL. The addition of the plasma fraction d greater than 1.21 g/ml proteins from abetalipoproteinemic subjects resulted in progressive decreases in cholesteryl ester and triglyceride transfer activities. The reduced activities of these transfer proteins may reflect (at least in part) the presence of an inhibitor(s) which is heat-stable and trypsin-sensitive.

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PubMed1984

Electrophysiological studies in five cases of abetalipoproteinemia.

Auditory brainstem responses (ABRs), visual and somatosensory evoked responses (VEPs and SEPs) and nerve conduction studies were conducted in 5 patients with abetalipoproteinemia. The ABRs were normal in all cases. The VEPs were of normal amplitude but of increased latencies in two patients. The four eldest patients had delayed cortical SEPs but normal peripheral sensory nerve conduction studies. The peripheral motor conduction velocities were normal in all cases. The peripheral sensory studies showed normal velocity when a response was seen; however, the amplitude of the response was often reduced or it was absent. The electrophysiological studies reported here support a model of axonal loss of large myelinated fibres with secondary demyelination in abetalipoproteinemia.

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PubMed2002

Abetalipoproteinemia-like lipid profile and acanthocytosis in a young woman with anorexia nervosa.

We report the case of a 17-year-old woman with anorexia nervosa (AN) who developed an abetalipoproteinemia-like lipid profile and acanthocytosis. These abnormalities resolved slowly as her nutritional status improved. We considered 3 possible causes of an abetalipoproteinemia-like lipid profile in AN: (1) depletion of hepatic substrate for apolipoprotein B synthesis, (2) lack of exogenous fatty acids with exhaustion of endogenous stores of triglycerides in adipose tissue, and (3) preservation of the lipoprotein lipase (LPL) mass. This unusual case provides important clues that enhance our understanding of lipid metabolism under exogenous and endogenous fat deprivation and highlights the pivotal role of LPL as a gatekeeper of the energy source.

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PubMed1988

Substrate specificity of plasma lecithin: cholesterol acyltransferase in abetalipoproteinemia.

The lecithin: cholesterol acyltransferase (LCAT) activity of lipoprotein-depleted plasma from a patient with abetalipoproteinemia has been assayed in a modified Glomset-Wright incubation system with three different normal lipoprotein substrates consisting of an authentic mixture of very low (VLDL), low (LDL) and high (HDL) density lipoproteins for the assay of total LCAT activity, HDL to assay alpha-LCAT activity and combined VLDL and LDL to assay beta-LCAT activity, respectively. Although reduced to about half the normal control values, both alpha- and beta-LCAT activities were present in the patient's plasma. It has been shown earlier that secretion of LCAT is linked to that of VLDL, but since patients with abetalipoproteinemia cannot form either chylomicrons or VLDL, our results suggest that a secretion of these triglyceride-rich lipoproteins do not seem to be a prerequisite for a basal secretion of beta-LCAT.

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PubMed1992

Absence of microsomal triglyceride transfer protein in individuals with abetalipoproteinemia.

Abetalipoproteinemia is a human genetic disease that is characterized by a defect in the assembly or secretion of plasma very low density lipoproteins and chylomicrons. The microsomal triglyceride transfer protein (MTP), which is located in the lumen of microsomes isolated from the liver and intestine, has been proposed to function in lipoprotein assembly. MTP activity and the 88-kilodalton component of MTP were present in intestinal biopsy samples from eight control individuals but were absent in four abetalipoproteinemic subjects. This finding suggests that a defect in MTP is the basis for abetalipoproteinemia and that MTP is indeed required for lipoprotein assembly.

Abetalipoproteinemia↗

PubMed1974

A study of the abnormal lipoproteins in abetalipoproteinemia.

The serum lipoproteins of five patients with abetalipoproteinemia (ABL) were separated by ultracentrifugation and then analyzed either intact or after delipidation. In accord with previous findings, all of the patients lacked serum particles with the characteristics of normal low-density lipoproteins (LDL) and of the LDL apoprotein as assessed by immunochemical methods. Each patient exhibited on every examination an abnormal particle, "LDL", which had the flotational properties of LDL, the polypeptide makeup of high-density lipoproteins HDL, the spectral and morphological characteristics of neither LDL nor HDL, and a relatively low content of cholesteryl esters. The HDL were abnormal in having a marked decrease in their total plasma content, an altered proportion of the subclasses HDL2 and HDL3, and a peculiar polypeptide distribution, comprising both normal and additional components, usually not seen in normal controls. The patients also exhibited a decrease of plasma lecithin-cholesterol acyl transferase (LCAT) activity which probably accounted for the low content of cholesteryl esters in both "LDL" and HDL, and in turn for the unusual appearance of "LDL" on electron microscopy. It is concluded that ABL is a disorder affecting all serum lipoprotein classes. Whether the abetalipoproteinemia previously described and noted in the current studies is related to or independent of the abnormalities observed in the other lipoproteins was not established. How the deficiency of LCAT activity, observed in all patients studied, contributed to some of the observed structural lipoprotein abnormalities also remained undetermined.

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PubMed1977

Decreased fluidity of red cell membrane lipids in abetalipoproteinemia.

Acanthocytic red cells in patients with abetalipoproteinemia are morphologically similar to the red cells in spur cell anemia. Fluidity of membrane lipids is decreased in spur cells due to their excess cholesterol content. Acanthocyte membranes have an increased content of sphingomyelin and a decreased content of lecithin. To assess the effect of this abnormality of acanthocyte membrane lipid composition on membrane fluidity, we studied red cells from five patients with abetalipoproteinemia and four obligate heterozygote family members. Membrane fluidity was measured in terms of microviscosity ( eta) at 37 degrees C, assessed by means of the fluorescence polarization of 1,6-diphenyl-1,3,5-hexatriene. It was increased from 3.2+/-0.1 poise in normals to 4.01-4.14 poise in acanthocytes. This was associated with an increase in the sphingomyelin/lecithin ratio from 0.84+/-0.08 in normals in 1.45-1.61 in acanthocytes. The eta of acanthocyte membranes was not influenced by the degree of vitamin E deficiency. Similar changes in eta were observed in liposomes prepared from red cell lipids. Heterozygotes had normal sphingomyelin/lecithin ratios and normal values for eta. The flow activation energy for viscosity, a measure of the degree of order in the hydrophobic portion of the membrane, was decreased from 8.3 kcal/mole in normal red cells to 7.2 kcal/mole in acanthocytes, indicating that acanthocyte membrane lipids are more ordered. Variations in the sphingomyelin/lecithin mole ratio of liposomes prepared from brain sphingomyelin and egg lecithin with equimolar cholesterol caused similar changes in both eta and activation energy. The deformability of acanthocytes, assessed by means of filtration through 3-mum filters, was decreased. These studies indicate that the increased sphingomyelin/lecithin ratio of acanthocytes is responsible for their decreased membrane fluidity. As in spur cells and in red cells enriched with cholesterol in vitro, this decrease in membrane fluidity occurs coincidentally with an abnormality in cell contour and an impairment in cell deformability.

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PubMed2001

Rickets as an unusual initial presentation of abetalipoproteinemia and hypobetalipoproteinemia.

OBJECTIVE: Description of rickets as an unexpected initial manifestation in two children with abetalipoproteinemia and hypobetalipoproteinemia, and elucidation of its pathophysiology in these conditions. METHODOLOGY: Two infants aged two and six months with abetalipoproteinemia and hypobetalipoproteinemia respectively had clinical rickets at presentation, confirmed radiologically and biochemically. Vitamin D intake and serum levels were measured and other causes of rickets were looked for. RESULTS: Vitamin D intake and laboratory studies levels were suggestive of rickets due to calcium deficiency instead of vitamin D deficiency. Healing of rickets occurred with dietary treatment of the malabsorption, without any dietary calcium or significant vitamin D supplementation. CONCLUSION: Steatorrhea-induced calcium malabsorption seems to be the most likely cause of rickets in this entity.

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PubMed1983

A case report of abetalipoproteinemia (Bassen-Kornzweig syndrome)--the first case in Japan.

The clinical and pathophysiological features of a case of abetalipoproteinemia in a 34-year-old patient are described. This patient is the first case reported in Japan. The patient was diagnosed as abetalipoproteinemia by confirming the Apo-B deficiency in the patient's serum and the slightly high cholesterol level in his mother's and borderline normal level in his father's. The patient had remarkably low lipid levels, acanthocytosis, and lipid malabsorption. An unusual feature of this case was that the patient had no neuromuscular or ocular manifestations. This was possibly related to his normal plasma vitamin A and E levels.

Abetalipoproteinemia↗

PubMedDate not supplied

Angioid streaks associated with abetalipoproteinemia.

Angioid streaks were observed in two patients with abetalipoproteinemia. The progression of the angioid streaks was minimal over the years that these patients received vitamin A and E supplementation, though in one patient the development of subretinal neovascular membranes within the angioid streaks was the cause of rapid central visual loss. The simultaneous appearance of two rare entities in unrelated individuals strengthens the relationship between these two disorders that has been suggested by previous case studies. The authors propose a common metabolic pathway involving trace element deficiencies that may account for this relationship as well as the association of angioid streaks with other rare disorders such as Paget's disease, hypoparathyroidism, lead poisoning, hyperphosphatemia, and a number of hemoglobinopathies. Their study of these two patients underscores the need for further investigations as to the role of copper, zinc and omega-3 fatty acids in the pathogenesis of retinopathy in abetalipoproteinemia.

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PubMed2006

Autopsy case of Dubin-Johnson syndrome with pneumonia and abetalipoproteinemia-like lipid profile.

We report the autopsy of a 79-year-old Japanese woman with Dubin-Johnson syndrome accompanied by pneumonia, an abetalipoproteinemia-like lipid profile and acanthocytosis. On admission, physical examination of the patient revealed malnutrition. Blood tests revealed marked inflammatory changes and mild liver dysfunction. Chest X-ray indicated bilateral pneumonia. Total cholesterol, low-density lipoprotein (LDL) cholesterol and triglyceride levels were 89 mg/dL, 5 mg/dL and 6 mg/dL, respectively. Peripheral blood smears revealed numerous acanthocytes. Despite the administration of antibiotics and nutritional support, the patient died. Autopsy revealed a black liver, atrophy of fat tissue on the mesentery, and pneumonia with bilateral pleural effusion. We believe that the abetalipoproteinemia-like lipid profiles in this case were caused by malnutrition and the inflammatory changes rather than the direct effects of Dubin-Johnson syndrome. We base this conclusion on the following three findings: 1) the patient's lipid profile before hospitalization was in the normal range, 2) her serum LDL cholesterol and triglyceride levels gradually increased after nutritional support began, and 3) blood tests revealed marked inflammatory changes (C-reactive protein 9.0 mg/dL; interleukin-6 16.4 pg/mL). This case provides important information that enhances our understanding of lipid metabolism under conditions of malnutrition and inflammation.

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PubMed1989

Angioid streaks associated with abetalipoproteinemia.

Angioid streaks were observed in a 31-year-old man with abetalipoproteinemia. Angioid streaks have now been described in hereditary spherocytosis, beta thalassemia, alpha thalassemia, sickle cell anemia, and acanthocytosis secondary to abetalipoproteinemia and hypobetalipoproteinemia. The nature of the association of angioid streaks and structural defects of hemoglobin and the red blood cell is not understood.

Abetalipoproteinemia↗

PubMedDate not supplied

Abetalipoproteinemia or Bassen-Kornzweig syndrome. Clinical, biochemical and electrophysiological features of two cases.

The clinical, biochemical and electrophysiologic features of two patients with abetalipoproteinemia, a 17 year old boy and his sister of 14, are reported. They are the second and third reports of this disease in Belgium. Diagnosis was made by the Apo-B deficiency in their serum and the normal levels in their parents'. According to other investigators we revealed in both cases deficiency of other apoproteins, indicating, that the metabolic defect affects all classes of plasma lipoproteins. EMG findings showed axonal neuropathy. Somatosensory evoked potentials demonstrated dorsal column dysfunction. Findings were consistent with the known neuropathology of abetalipoproteinemia and of vitamin E deficiency syndromes. The therapeutic role of vitamin E is discussed.

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PubMed1979

Immunofluorescence studies of apolipoprotein B in intestinal mucosa. Absence in abetalipoproteinemia.

During fat absorption, active synthesis of cholesterol, phospholipids, and specific apolipoproteins are required for chylomicron formation and secretion. In the inherited disease abetalipoproteinema, chylomicrons cannot be made in response to fat feeding, and they as well as low and very low density lipoproteins are completely absent from plasma. The genetic defect in the disease is presumed to be an inability to synthesize apolipoprotein B, the apoprotein common to all the above lipoprotein classes, but such a defect has not been directly demonstrated. With peroral intestinal biopsies and immunofluorescence and intracellular localization of apolipoprotein B within jejunal epithelial cells of five normal subjects and have shown that its content increases markedly after fat feeding. In two patients with abetalipoproteinemia no apolipoprotein B was seen by immunofluorescence techniques in the jejunal mucosa in the fasting state or after a fatty meal. Intestinal synthesis of apolipoprotein B appears not to occur in abetalipoproteinemia.

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PubMed1987

[Abetalipoproteinemia. Apropos of 2 cases].

The cases of two sisters with abetalipoproteinemia are reported. Both presented the complete clinical and biological features of the disease: ataxia, retinitis pigmentosa, lack of apolipoprotein B, chylomicrons, LDL and VLDL, reduced titers of serum cholesterol and triglycerides, acanthocytosis, very low levels of serum vitamin A and E. Abetalipoproteinemia is a rare autosomal inherited disease. It is usually revealed during early childhood by steatorrhea and failure to thrive; ataxia and retinitis pigmentosa appear later. The originality of these two cases stems from: 1) their late and fortuitous diagnosis: the first sister was investigated at the age of 42 after the discovery of a vitamin K induced coagulation disorder. The other sister was 39 when she was routinely examined as a family member; 2) the presence of constipation without any other suggestive digestive complaint. However, white discoloration of the duodenal mucosa seen at endoscopy and lipid droplets within the intestinal absorptive cells at biopsy were characteristic. Barium studies showed diffuse involvement of the small bowel which was displaced by an enlarged sigmoid. Treatment consists of administration of vitamin A and vitamin E which prevent or delay ocular and neurologic symptoms. Vitamin K is associated whenever necessary.

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PubMed1983

Cholesterol turnover and metabolism in two patients with abetalipoproteinemia.

Total body turnover of cholesterol was studied in two patients with abetalipoproteinemia, a 32-year-old man and a 31-year-old woman. The patients received [14C]cholesterol intravenously, and the resulting specific activity-time curves (for 40 and 30 weeks, respectively) were fitted with a three-pool model. Parameters were compared with those from studies of cholesterol turnover in 82 normal and hyperlipidemic subjects. A three-pool model gave the best fit for the abetalipoproteinemic patients, as well as for the 82 previously studied subjects, suggesting general applicability of this model. Cholesterol production rates in the two abetalipoproteinemic subjects (0.82 and 0.89 g/day) were close to values predicted for persons of their body weight. Thus, total body turnover rate of cholesterol was quite normal in abetalipoproteinemia, confirming previous reports. Very low values (9.2 and 8.4 g) were found for M1, the size of the rapidly exchanging compartment pool 1, in the two abetalipoproteinemic subjects. These values were well below the values predicted (from the comparison study population) for normal persons of this size with low plasma cholesterol levels. For one patient, total body exchangeable cholesterol was very low, although not significantly below the predicted values for a person of his size. In the second patient, the observed estimate for total body exchangeable cholesterol was well within the range of values predicted for persons of her size with low to extremely low cholesterol levels.(ABSTRACT TRUNCATED AT 250 WORDS)

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PubMed1982

[Asymptomatic abetalipoproteinemia associated with partial apoprotein B deficiency: a familial case report].

The authors report a case of familial asymptomatic abetalipoproteinemia. The propositus has total abetalipoproteinemia associated with a partial apoprotein B defect. His two daughters have a subtotal betalipoprotein deficiency. This familial case, with autosomal dominant transmission, seems different from other reports. It supports the hypothesis that the primary involvement is a deficiency in apoprotein B synthesis, which appears more closely correlated with clinical symptoms.

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