In which type of hypertriglyceridemia are chylomicron & VLDL remnants increased

Question 26

In which type of hypertriglyceridemia are chylomicron & VLDL remnants increased .

a.       I

b.      IIa

c.       III

d.      IV

Answer :

C) Type III

Reference :

Harper 27^th Edition Page 239

Discussion

Lipoproteins have been classified on the basis of their densities into five major classes:(1) chylomicrons, (2) very low density lipoproteins (VLDL), (3) intermediate-density lipoproteins (IDL), (4) LDL, and (5) high-density lipoproteins (HDL).

Explanation

Name	Defect	Remarks
Familial Type III Hyperlipoproteinemia (Broad beta disease, remnant removal disease, familial dysbetalipoproteinemia)	Deficiency in remnant clearance by the liver due to abnormality in apo E. Patients lakc Isoforms E3 and E4 and have only E2 which does not react with E receptor

Comments

This answer is based on Harper. There are few differences between the table given in Harper (Table 26.127^th Edition Page 239) and Table 344-4 in Harrison (15^th Edition). If the question had asked about Chylomicrons alone or VLDL alone, then the answer would have to be based on Harrison

Characteristics of Common Hyperlipidemias (From Harrison)
		Lipopoteins
Lipid Phenotype	Plasma Lipid Levels, mmol/L (mg/dL)	Elevated	Phenotype	Clinical Signs
ISOLATED HYPERCHOLESTEROLEMIA
Familial hypercholesterolemia	Heterozygotes: total chol = 7-13 (275-500)	LDL	IIa	Usually develop xanthomas in adulthood and vascular disease at 30-50 years
	Homozygotes: total chol > 13 (>500)	LDL	IIa	Usually develop xanthomas and vascular disease in childhood
Familial defective apo B100	Heterozygotes: total chol = 7-13 (275-500)	LDL	IIa
Polygenic hypercholesterolemia	Total chol = 6.5-9.0 (250-350)	LDL	IIa	Usually asymptomatic until vascular disease develops; no xanthomas
ISOLATED HYPERTRIGLYCERIDEMIA
Familial hypertriglyceridemia	TG = 2.8-8.5 (250-750) (plasma may be cloudy)	VLDL	IV	Asymptomatic; may be associated with increased risk of vascular disease
Familial lipoprotein lipase deficiency	TG > 8.5 (>750) (plasma may be milky)	Chylomicrons	I, V	May be asymptomatic; may be associated with pancreatitis, abdominal pain, hepatosplenomegaly
Familial apo CII deficiency	TG > 8.5 (>750) (plasma may be milky)	Chylomicrons	I, V	As above
HYPERTRIGLYCERIDEMIA AND HYPERCHOLESTEROLEMIA
Combined hyperlipidemia	TG = 2.8-8.5 (250-750) Total chol = 6.5-13.0 (250-500)	VLDL, LDL	IIb	Usually asymptomatic until vascular disease develops; familial form may also present as isolated high TG or an isolated high LDL cholesterol
Dysbetalipoproteinemia	TG = 2.8-5.6 (250-500) Total chol = 6.5-13.0 (250-500)	VLDL, IDL; LDL normal	III	Usually asymptomatic until vascular disease develops; may have palmar or tuboeruptive xanthomas
NOTE: total chol, the sum of free and esterified cholesterol; LDL, low-density lipoprotein; TG, triglycerides; VLDL, very low density lipoproteins; IDL, intermediate-density lipoprotein.

Tips

There is an association between patients possessing the apo E4 allele and the incidence of Alzheimer’s disease. Apparently apo E4 binds more avidly to beta amyloid found in neuritic plaques