The pilot study has the target to evaluate the outcomes of two novel mutations in the gene of Apolipoprotein B (ApoB). ApoB is the main part of the low-density lipoprotein (LDL). LDL is the main transporter of cholesterol from the liver to the periphery. The two novel mutations lead to a heavily truncated Apolipoprotein B. Therefore the patients show severely decreased ApoB and LDL-Cholesterol levels. The acquired disease is known as "Familial Hypobetalipoproteinemia". Beside the protection from cardiovascular disease due to decreased LDL-Cholesterol, patients tend to show elevated serum aminotransferases, fatty liver and occasional cases of cirrhosis and carcinoma.

To elucidate the differences in lipoprotein assembly the investigators aim to characterize the changes due to the mutations in the patients. Family members not carrying the mutations are the control group. The assessment includes lipoprotein fractionation, MRI scans of the liver and a thorough assessment of medical history of all patients to look for potential side effects of the mutation.

The only intervention needed for the study is to draw blood samples of every participant. The necessary positive vote from the ethics committee of the Medical University of Innsbruck is given.

Inclusion Criteria:

• Full legal age
• Written Informed Consent
• Diagnosed hypobetalipoproteinemia
• Exception of it are the controls
• Controls have to be family members
• Exclusion of a truncating mutation in the ApoB gene

Exclusion Criteria:

• No diagnosed hypobetalipoproteinemia
• No truncating mutation in the Apo B gene
• Exception of it ar the controls

The participants descend from two families. Each family carries a novel truncating mutation in the ApoB gene. The family members decided to participate in our pilotstudy to elucidate the changes caused by the mutations. Familial hypobetalipoproteinemia is a codominant disorder, so family members not carrying the mutations serve as control group.