Microsomal triglyceride transfer protein polymorphisms and lipoprotein levels in type 2 diabetes.

Abstract

BACKGROUND:

Microsomal triglyceride transfer protein (MTP) regulates the assembly of chylomicrons in the intestine and very-low-density lipoprotein (VLDL) in the liver. Common polymorphisms have been described that do not affect lipoproteins in non-diabetic subjects. Their effect in diabetes has not been described in a Caucasian population.

AIM:

To investigate the association of these three common polymorphisms with lipoproteins in type 2 diabetes.

METHODS:

Eighty-two patients consumed a high-fat test meal. Chylomicron and VLDL apoB48, apoB100, cholesterol, triglycerides and phospholipids were measured fasting, and at 4 and 6 h postprandially. MTP genotyping was performed by PCR-RFLP.

RESULTS:

Thirty-three subjects were heterozygous for the -493 G/T substitution. These patients had significantly lower LDL cholesterol (3.0 +/- 0.2 vs. 3.5 +/- 0.1 mmol/l, p < 0.02). In the postprandial period, they had higher levels of apoB48 in the VLDL fraction (4 h, 7.0 +/- 1.4 vs. 2.9 +/- 0.4 microg/ml plasma, p < 0.002; 6 h, 6.4 +/- 1.0 vs. 3.5 +/- 0.5 microg/ml plasma, p < 0.05). In the VLDL fraction there was significantly less cholesterol at 4 and 6 h (p < 0.05). The -400 A/T substitution gave very similar lipoprotein results, but there was significant linkage dysequilibrium between the two polymorphisms. No association was found between the -164 T/C polymorphism and either plasma lipids or the postprandial lipid profile. ApoE genotype was also examined, but did not influence the above results.

DISCUSSION:

The common -493 G/T MTP polymorphism is associated with changes in VLDL and LDL in Type 2 diabetic patients. The importance of the changes in apoB48-containing small particles requires further investigation. The significantly lower LDL cholesterol suggests that this polymorphism may confer protection against atherosclerosis in type 2 diabetes.

• Authors: C Phillips, K Mullan, D Owens, G H Tomkin
• Journal: QJM : monthly journal of the Association of Physicians (QJM) Vol. 97 Issue 4 Pg. 211-8 (Apr 2004) ISSN: 1460-2725 [Print] England
• PMID: 15028851 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Carrier Proteins
• Chylomicrons
• Lipoproteins, VLDL
• microsomal triglyceride transfer protein
• Cholesterol

Topics

• Aged
• Carrier Proteins (genetics)
• Cholesterol (blood)
• Chylomicrons (blood)
• Diabetes Mellitus, Type 2 (blood, genetics)
• Female
• Humans
• Lipoproteins, VLDL (blood, genetics)
• Male
• Middle Aged
• Polymorphism, Genetic