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Unusual familial lipoprotein C-III associated with apolipoprotein C-III-O preponderance
Insights
A rare genetic lipoprotein disorder was identified in a family, characterized by high levels of apolipoprotein C-III-O in very low density and high density lipoproteins. This condition appears to be inherited without clinical symptoms.
Area of Science:
- Biochemistry
- Genetics
- Lipid Metabolism
Background:
- Lipoprotein analysis is crucial for understanding lipid metabolism and associated disorders.
- Apolipoprotein C-III (apoC-III) is a key regulator of triglyceride metabolism and exists in polymorphic forms.
Observation:
- A 63-year-old female subject presented with unusually high concentrations of apolipoprotein C-III-O within her very low density lipoprotein (VLDL) and high density lipoprotein (HDL) fractions.
- This distinct lipoprotein phenotype was identified using polyacrylamide gel electrophoresis, isoelectric focusing, and sialidase treatment.
Findings:
- The unusual lipoprotein profile, characterized by a preponderance of apoC-III-O, was inherited by two of the subject's four children.
- Lipid profiles, including triacylglycerols and cholesterol in VLDL, LDL, and HDL, remained within normal ranges for affected individuals.
- Serum apoC-III levels were also within normal limits, as assessed by rocket immunoelectrophoresis.
Implications:
- These findings suggest a novel, genetically determined lipoprotein disorder characterized by apoC-III-O.
- Further research into this genetic variant may elucidate new mechanisms in lipoprotein metabolism and hereditary dyslipidemias.
- This discovery highlights the importance of investigating rare genetic variations in understanding complex lipid disorders.
Abstract:
Among 256 consecutive subjects so far studied in our laboratory, we found one subject (a 63-year-old female) whose very low density lipoprotein (VLDL) and high density lipoprotein (HDL) contained unusually high amounts of apolipoprotein C-III-O among apolipoprotein C-III polymorphic forms. Identification of apolipoprotein C-III-O was achieved by a combination of basic polyacrylamide gel electrophoresis, isoelectric focusing and sialidase treatment of plasma apolipoproteins. This unusual lipoprotein was inherited by two of her four children without the manifestation of clinical symptoms. Triacylglycerols and cholesterol concentrations of VLDL, low density lipoprotein (LDL) and HDL fractions, and serum apolipoprotein C-III levels of the three subjects with apolipoprotein C-III-O were within the normal range, as estimated by rocket immunoelectrophoresis. Our results clearly demonstrated that the unusual lipoproteins with the preponderance of apolipoprotein C-III-O among apolipoprotein C-III polymorphic forms were genetically determined. These cases may be a new type of genetic lipoprotein disorder.