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Mechanisms of Low Levels of Apolipoprotein B

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details. Identifier: NCT00005565
Recruitment Status : Completed
First Posted : May 26, 2000
Last Update Posted : July 29, 2016
Information provided by:
National Heart, Lung, and Blood Institute (NHLBI)

Brief Summary:
To determine mechanisms of low levels of apolipoprotein B.

Condition or disease
Cardiovascular Diseases Heart Diseases Hypobetalipoproteinemia

Detailed Description:


Elevated apoB levels are associated with an increased risk of coronary heart disease. Hypobetalipoproteinemia (HBLP) is characterized by apoB levels less than the 5 percentile. Dr. Welty, the principal investigator, sequenced mutations for truncated forms of apoB-67, apoB-55 and apoB-44.4 which causes HBLP, described a kindred from the Framingham Heart Study with HBLP due to an unidentified apoB gene mutation and purified apoB-67 containing lipoprotein particles. Heterozygous apoB-67 subjects have one normal allele making apoB-100; therefore, apoB levels would be predicted to be at least 50 percent of normal; however, they are 24 percent of normal. Dr. Welty has shown that these lower than expected levels result from decreased production of VLDL apoB-100, LDL apoB-100 and apoB-67, increased catabolism of VLDL apoB-100, and increased direct removal of apoB-67 from VLDL.


The first aim is to locate the apoB gene mutation in the Framingham kindred. The second aim is to perform stable isotope studies in the apoB-55 and apoB-44.4 kindreds to determine if apoB metabolism for these shorter truncations is similar to that for apoB-67. In aim three, apoB-100 synthesis is studied in heterozygous apoB-70 transgenic mice. If it is 25-25 percent of normal litter mates, the mechanism for this reduction in apoB-100 levels will be studied in hepatocytes isolated from the transgenic mice. In specific aim 4, size and composition of VLDL are compared in apoB-67 subjects and controls to determine if larger size or compositional changes account for the faster catabolism of VLDL apoB-100. The study has been extended through June 2007.

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Study Type : Observational
Study Start Date : August 1997
Actual Primary Completion Date : June 2002
Actual Study Completion Date : June 2002

Information from the National Library of Medicine

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Ages Eligible for Study:   up to 100 Years   (Child, Adult, Older Adult)
Sexes Eligible for Study:   Male
Accepts Healthy Volunteers:   No
No eligibility criteria

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its identifier (NCT number): NCT00005565

Sponsors and Collaborators
National Heart, Lung, and Blood Institute (NHLBI)
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OverallOfficial: Francine Welty Beth Israel Deaconess Medical Center
Layout table for additonal information Identifier: NCT00005565    
Other Study ID Numbers: 5114
R01HL056895 ( U.S. NIH Grant/Contract )
First Posted: May 26, 2000    Key Record Dates
Last Update Posted: July 29, 2016
Last Verified: January 2008
Additional relevant MeSH terms:
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Cardiovascular Diseases
Heart Diseases
Lipid Metabolism, Inborn Errors
Metabolism, Inborn Errors
Genetic Diseases, Inborn
Lipid Metabolism Disorders
Metabolic Diseases