Analyse von Genvarianten des Gewebeinhibitors der Metalloproteinase-2 (TIMP-2) bei Patienten mit abdominalem Aortenaneurysma

Zusammenfassung

Einleitung: Die Entstehung von abdominalen Aortenaneurysmen (AAA) wird durch eine Veränderung der extrazellulären Matrix (ECM) und Schwächung der Gewebetextur in der Gefäßwand erklärt. Matrixmetalloproteinasen (MMP) bauen die extrazelluläre Matrix ab und spielen eine wichtige Rolle im Umbau der Gewebetextur in arteriellen Gefäßen. Ihre Aktivität wird durch deren Inhibitoren reguliert. Eine erniedrigte Expression der Tissue Inhibitors of Metalloproteinase-1 und -2 (TIMP-1 und -2) wurde in mehreren Studien in Aortenaneurysmawänden nachgewiesen. Ziel unserer Studie war es, die Bedeutung von Genvarianten (Single nucleotide polymorphisms, SNPs) des TIMP-2-Gens im Hinblick auf die Ätiologie eines AAA zu untersuchen und eine bereits beschriebene Assoziation eines SNPs (TIMP-2 303G > A) mit dem Auftreten von AAA an einer deutschen Population zu validieren. Methoden: Aus der DNS von 50 Patienten mit AAA und 41 Personen aus der Normalbevölkerung wurden die komplette kodierende Region und Abschnitte der Promotorregion des TIMP-2-Gens nach der Methode von Sanger sequenziert mit anschließender Detektion auf dem automatischen Laserfluoreszenzsequenzierer (A. L. F. express™). Jede Sequenzierung wurde mit einer Referenz verglichen und ausgewertet. Die statistische Auswertung der Genotyp- und Allelfrequenzen erfolgte mittels Odds Ratio, exaktem 95 % Konfidenzintervall und Vergleich der Gruppen mit dem Cochran-Armitage-Trend-Test. Ergebnisse: Neben 5 beschriebenen Polymorphismen konnte eine weitere Sequenzvariante (231 + 23C > T) detektiert werden. Die beschriebene Assoziation des 303G > A SNPs mit dem Phänotyp konnte an unserem Patientenkollektiv nicht bestätigt werden (p = 0,648). Der Genotyp CT des Polymorphismus –479C > T trat in der AAA-Gruppe häufiger auf als in der Kontrollgruppe (p = 0,054). Schlussfolgerung: Bei der Analyse des TIMP-2-Gens konnte ein neuer Polymorphismus identifiziert werden. Die vorbeschriebene Assoziation des 303G > A SNPs im TIMP2-Gen für den Phänotyp Aortenaneurysma konnte in unserem Patientenkollektiv nicht bestätigt werden. Es zeigte sich jedoch eine schwach signifikante Assoziation für den Genotyp CT im SNP–479C > T mit dem Auftreten von Aortenaneurysma. Dieses Ergebnis muss an einer zweiten größeren Stichprobe bestätigt werden.

Abstract

Background: The formation of sporadic abdominal aortic aneurysm (AAA) is explained by a remodelling of the extracellular matrix (ECM) and breakdown of structural components of the vascular wall. Matrix metalloproteinases are the principle matrix-degrading proteases and are known to play a major role in the remodelling of the extracellular matrix in arterial vessels. Their activity is controlled by tissue inhibitors of metalloproteinases (TIMPs). Decreased TIMP-1 and TIMP-2 expression in the extracellular matrix of the walls of AAAs has been demonstrated in several studies. This case-control study was designed to investigate the possible impact of genetic variants of the TIMP-2 gene in the aetiology of AAA and to reproduce a recently described significant difference in allele frequency of the SNP 303G > A in a German population. Methods: TIMP-2 single nucleotide polymorphisms (SNPs) were analysed in a study sample of 50 patients with AAA and 41 controls. Differences in genotype and allele frequencies of the identified polymorphisms were determined after sequencing the entire coding region and selected parts of the promoter using the automated laser fluorescence technique. Results: Six polymorphisms were identified, one of which is described for the first time, located in the intron, (231 + 23C > T). An association of the SNP 303G > A with the phenotype was not confirmed in our study (p = 0.648). However, the CT genotype of the SNP –479C > T was more frequent in patients with AAA than in the control group (p = 0.054). Conclusions: In our analysis of the TIMP-2 gene, we identified one new SNP. A previously published association of the SNP 303G > A with the phenotype could not be validated in our population. However, we detected an association for the CT genotype of one polymorphism in the promoter region (g-479C > T) and AAA. This result has to be proved in a second study sample.

Schlüsselwörter

abdominales Aortenaneurysma - Polymorphismus - Genetik - TIMP-2

Key words

abdominal aortic aneurysm - polymorphism - genetics - TIMP-2

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