Hyperlipoproteinemia

 A) Primary Hyperlipoproteinemia

TYPE	CLASSIFICATION	BIOCHEMICAL DEFECT	INHERITANCE	PLASMA LIPIDS AND LIPOPROTEINS	CLINICAL FEATURES
I.	Familial lipoprotein lipase deficiency(Hyperchylomicronemia)	Deficiency of lipoprotein lipase. A variant of this diseases can be produced by deficiency of apo CII.	Autosomal recessive	TG↑, cholesterol may also be increased, Chylomicrons ++, VLDL↑, HDL and LDL ↓.Refrigeration test confirms the presence of chylomicrons in serum	Present in early childhood, Eruptive xanthomas, Recurrent abdominal pain, no premature cardiovascular disease
II.	Familial Hypercholesterolemia(FHC)	No enzyme deficiency but there is increased synthesis of apo- B protein and there is impaired degradation of LDL	Autosomal dominant	LDL ↑, total cholesterol ↑, VLDL  and TG are also raised	Xanthomas, corneal arcus, increased risk of premature Cardiovascular disease.
III.	Familial Dysbeta lipoproteinemiaAlso called- Broad beta disease , ‘Remnant removal disease”	Increase concentration of apo-E, increased synthesis of Apo B, conversion of normal VLDL to IDL and its degradation without conversion to LDL. Defect in Remnant removal.	Autosomal dominant	LDL↑, VLDL↑, actual rise in IDL which appears as Broad beta band on electrophoresis. TG↑, cholesterol may also be increased.	Tuberous and Palmar xanthomas, increased risk of premature Cardiovascular disease and peripheral vascular disease.
IV.	Familial Hypertriglyceridemia(FHTG)	Increased synthesis  and decreased catabolism of endogenous TGs	Autosomal dominant	Hyper pre beta lipoproteinemia VLDL↑, TG and cholesterol also↑, α and β-lipoproteins are subnormal (HDL↓ and LDL↓). There is associated impaired Glucose Tolerance	Presents in early childhood, and is commonly associated with CHD, Diabetes Mellitus, Alcoholism and  obesity
V.	Combined Hyperlipidemia	Usually secondary to other disorders like obesity, excessive alcohol intake, renal failure and pancreatitis etc. Exact biochemical defect is not known	Autosomal dominant	Complex lipoprotein pattern, Increase in both chylomicrons and pre β-lipoproteins (VLDL), TG and cholesterol also↑↑, α and β-lipoproteins are subnormal (HDL↓ and LDL↓).	Xanthomas are frequently present impaired glucose tolerance, frequently found associated with CHD, Diabetes Mellitus, Alcoholism and  obesity

B) Secondary Hyperlipoproteinemia

S. .No	Disease	Serum total Cholesterol	Serum triglycerides
1.	Diabetes Mellitus	Increased	Increased
2.	Nephrotic syndrome	Increased	Increased
3.	Hypothyroidism	Increased	Increased
4.	Biliary obstruction	Increased	Normal
5.	Pregnancy	Increased	Normal
6.	Alcoholism	Normal	Increased
7.	Oral contraceptives	Normal

Hypolipoproteinemia

Disease	Biochemical defect	Inheritance	Laboratory findings	Clinical manifestations
Familial Hypobetalipoproteinemia	Inability to synthesize ApoB100 and Apo-B48	Autosomal dominant	LDL between 10 to 50 % of normal, Cholesterol low but Triglycerides and Chylomicrons normal.	Mostly asymptomatic, but there is decreased risk of CHD
Abetalipoproteinemia	No synthesis or secretion  of Apo B containing lipoproteins	Rare inherited disease	VLDL↓, LDL↓↓, B-100↓, B-48↓, decrease in TG and a marked ↓in Serum total cholesterol, prolonged prothrombin time.	Malabsorption, mental and physical retardation, acanthocytosis, Atypical retinitis pigmentosa, fatty infiltration of intestinal mucosal cells and liver.
Hypoalphalipoproteinemia	Not known	Autosomal dominant	HDL↓, Cholesterol and TGs normal	Increased risk of CHD
Familial Alpha lipoprotein deficiency(Tangier’s disease)	Deficiency of alpha lipoprotein. Cholesteryl esters are deposited in the reticulo endothelial system, but functions of major organs are not affected	Autosomal recessive	Low or absent HDL, Lack of Alpha band on electrophoresis.	Orange yellow tonsils and adenoids, muscle weakness, atrophy, recurrent peripheral neuropathies and depressed tendon reflexes. The pharyngeal and rectal mucosa is also orange colored.(The orange color is due to deposition of cholesteryl esters.) There is increased predisposition to Atherosclerosis.

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