Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0024523 (malabsorption)
 7,319 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We describe the clinicoepidemiologic features, natural history, and therapeutic manipulations in three Greek patients with A-beta-lipoproteinemia (two brothers aged 15 and 29 years, respectively, and one sister aged 30 years). Diarrhea started in infancy in the two brothers and from the age of 13 in the sister. During the second decade of life, central nervous system symptoms became prominent, with fatigue and disturbance in gait and balance. Night blindness developed at a later phase of the disease in the brothers, whereas cavus developed in both legs in the sister. Apolipoprotein B was absent in all patients, and each had more than 50% of acanthocytes present on peripheral smear. The diagnosis of A-beta-lipoproteinemia was established on the basis of small bowel histology and serum lipid estimations. Family studies revealed normal lipid profiles in all healthy members. The human leukocyte antigen (HLA) pattern in the two most severely affected patients was identical. The only detectable difference between the severely ill patients and other members of the family, however, was homozygosity for the HLA B18 antigen, whereas the third patient had no alleles for the HLA B18 antigen. Treatment consisted of a low-fat diet and high doses of vitamins A and E. A modified diet substituting medium-chain triglycerides for dietary fat was also given, with significant improvement in the nutritional status of patients but not in symptoms related to advanced disease, such as retinal and cardiac manifestations. We conclude that the course of the disease in untreated patients is characterized by continuous symptoms. Some of the symptoms, however, especially those related to malabsorption, as well as some anthropometric parameters can be improved by the application of a modified diet including medium-chain triglycerides. We suggest the routine measurement of plasma lipids and apoproteins not only in children with failure to thrive, with unexplained malabsorption, or with neurologic symptoms, but also in adults with chronic diarrhea accompanied by neurologic symptoms or clinical and laboratory signs of malabsorption.
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PMID:A-beta-lipoproteinemia: clinical and laboratory features, therapeutic manipulations, and follow-up study of three members of a Greek family. 960 Mar 71

Apolipoprotein B-containing lipoproteins (B-lps) are essential for the transport of hydrophobic dietary and endogenous lipids through the circulation in vertebrates. Zebrafish embryos produce large numbers of B-lps in the yolk syncytial layer (YSL) to move lipids from yolk to growing tissues. Disruptions in B-lp production perturb yolk morphology, readily allowing for visual identification of mutants with altered B-lp metabolism. Here we report the discovery of a missense mutation in microsomal triglyceride transfer protein (Mtp), a protein that is essential for B-lp production. This mutation of a conserved glycine residue to valine (zebrafish G863V, human G865V) reduces B-lp production and results in yolk opacity due to aberrant accumulation of cytoplasmic lipid droplets in the YSL. However, this phenotype is milder than that of the previously reported L475P stalactite (stl) mutation. MTP transfers lipids, including triglycerides and phospholipids, to apolipoprotein B in the ER for B-lp assembly. In vitro lipid transfer assays reveal that while both MTP mutations eliminate triglyceride transfer activity, the G863V mutant protein unexpectedly retains ~80% of phospholipid transfer activity. This residual phospholipid transfer activity of the G863V mttp mutant protein is sufficient to support the secretion of small B-lps, which prevents intestinal fat malabsorption and growth defects observed in the mttpstl/stl mutant zebrafish. Modeling based on the recent crystal structure of the heterodimeric human MTP complex suggests the G865V mutation may block triglyceride entry into the lipid-binding cavity. Together, these data argue that selective inhibition of MTP triglyceride transfer activity may be a feasible therapeutic approach to treat dyslipidemia and provide structural insight for drug design. These data also highlight the power of yolk transport studies to identify proteins critical for B-lp biology.
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PMID:A point mutation decouples the lipid transfer activities of microsomal triglyceride transfer protein. 3276 60