Lipoproteins Flashcards
How is cholesterol transported around the blood?
70% as low density lipoproteins
17% as high density lipoproteins
What happens to cholesterol once it enters the liver?
It down-regulates the activity of HMG CoA Synthase (cholesterol synthesis)
7 alpha OHxylase will transform it into bile acids
MTP will transform it into lipoproteins
How are triglycerides transported in the body?
The enter through the small intestine in their largest form, chylomicrons.
They are then broken down to free fatty acids and processed in the liver
Name 4 causes of primary hypercholesterolaemia
- Familial hypercholesterolaemia
- Polygenic hypercholesterolaemia
- Familial hyperalphalipoproteinaemia
- Phytosterolaemia
Describe familial hypercholesterolaemia
This can be homozygous (1:1,000,000) or heterozygous (1:500).
It is an autosomally dominant inheritance and most commonly has defects in the LDL receptor gene. It can also be as a result of PCSK9 gene malformations and apoB
Describe polygenic hypercholesterolaemia
This is a mixed picture that is not completely known
What is familial hyperalphalipoproteinaemia
Usually a deficiency of CETP, causing high cholesterol
What is phytosterolaemia?
A malformation in ABC G5 and G8 which allows plant cholesterol to enter also, raising cholesterol levels
What are the clinical signs of familial hypercholesterolaemia?
- Corneal arcus at a young age
- Xanthelasma at a young age
Name 3 causes of primary hypertriglyceridaemia
- Familial Type I
- Familial Type IV
- Familial Type V
What is Familial Type I hypertriglyceridaemia?
A mutation in lipoprotein lipase causing a high amount of chylomicrons
What is Familial Type IV hypertriglyceridaemia?
An increased synthesis of triglycerides, causing a high plasma concentration of VLDLs
What is Familial Type V hypertriglyceridaemia
A possible deficiency in ApoA, causing a mixed picture of chylomicrons and VLDL in the plasma
How can you differentiate between the different causes of primary hypertriglyceridaemia?
Collect plasma and let it sit and cool.
- Chylomicrons will rise (Type I)
- VLDLs will stay in the suspension (Type IV)
- If there is both, type V
Name 3 causes of primary hyperlipidaemia
- Familial combined hyperlipidaemia
- Familial dysbetalipoproteinaemia
- Familial hepatic lipase deficiency
