MMP-9 haplotypes and carotid artery atherosclerosis: An association study introducing a novel multicolour multiplex RealTime PCR protocol

Background: Among other matrix metalloproteinases (MMPs), gelatinase B (MMP-9) is discussed to be associated with the pathogenesis of vascular diseases. Two single nucleotide polymorphisms (SNPs) of the MMP-9 gene, C-1562T in the promoter region and a G/A transition in exon 6 (R + 279Q), have been addressed in previous association studies which, however, produced conflicting results. Material and methods: A novel multiplex RealTime PCR protocol for the fast and simultaneous detection of both polymorphisms is presented, which was used for genotyping 1737 participants of a prospective study investigating genetic factors influencing the progression of atherosclerosis. Results: Haplotype analysis revealed -1562C/+279Q as the major haplotype in this population. Allelic distribution of the C-1562T polymorphism was consistent with data published for similar cohorts; however, we found that R + 279Q allelic distribution appears to vary significantly among Caucasian populations. Considering clinical data available from 1487 participants, we found significant associations between the presence of atherosclerotic plaque and the CA-haplotype in men (P = 0·028, phi = 0·08), and between the AG variant of exon 6 and common carotid artery intima-media thickness (CIMT) in women (P = 0·004, Eta² = 0·019). Conclusions: In summary, our results demonstrate associations of MMP-9 genotypes with different stages of carotid atherosclerosis.