To explore the possible implications of HLA-DRB1*04 alleles in patients with type 2 DM and macroangiopathy

Previous studies examining the molecular etiology of diabetes mellitus in China and abroad have mainly focused on the relationship between HLA and type 1 diabetes mellitus (DM) (1-3). Due to the complexity of type 2 DM heredity, few researchers have studied the correlation between type 2 DM and HLA. In recent years, it has been suggested that the development of coronary heart disease (CHD) in diabetic individuals is not merely a complication of diabetic macroangiopathy. CHD and diabetic macroangiopathy share some genetic associations. Previous studies have demonstrated that certain HLA*DRB1*04 subtypes are associated with an increased risk of cardiovascular disease.

Experimental methods: For genomic DNA extraction, 3-5ml venous blood samples were collected from all patients. Coagulation was prevented using EDTA.

The procedure for PCR amplification was as follows: denaturing for 100s at 96°C, annealing for 60s at 63°C, 1 cycle; denaturing for 10s at 96°C, annealing for 60s at 63°C, 9 cycles; denaturing for 10 s at 96°C, annealing for 30 s at 59°C; extending for 30 s at 72°C, 20 cycles; maintaining at 4°C. Analyzing PCR products stained by Ethidium Bromide on 2.5% agarose gel electrophoresis. Bands were observed using an ultraviolet light and a biological imaging system.

Statistical method: The degree of agreement with Hardy-Weinberg equilibrium was determined using the χ2 test. A t-test was employed for comparison of CRP levels (M ± s) and a χ2 test was performed to compare allelic frequencies. The relative risk rate (RR) was calculated as (Number of patients with the gene×Number of people in control group without the gene) divided by (Number of people in control group with the gene×Number of the patients without the gene). PC was calculated using Fisher's method if χ2 > 3.84.

Inclusion Criteria:

• clinical CHD (such as angina pectoris, myocardial infarction) diagnosed by dynamic electrocardiogram and ultrasonic cardiogram;
• coronary atherosclerosis confirmed by coronary angiographic examination;
• cerebral infarction diagnosed by cerebral CT;
• common carotid artery intimal-media thickness (IMT) ≥1.2 mm measured by Doppler ultrasonic examination;
• extensive irregular stenosis of a lower extremity artery (diameter < 3mm) or segmentally obstructed.

Exclusion Criteria:

• age < 20 years
• age > 60 years

150 healthy blood donors without a family history of diabetes mellitus at the Harbin Blood Disease Research Center were enrolled in the study, and 320 outpatients and hospitalized patients of type 2 diabetes mellitus from the First and Second Affiliated Hospital of Harbin Medical University.