GT microsatellite repeats in the heme oxygenase-1 gene promoter associated with abdominal aortic aneurysm in Croatian patients

Abdominal aortic aneurysm (AAA) is a complex genetic disorder, caused by unfavorable interplay of different genetic and environmental risk factors. The number of (GT)n repeats in the heme oxygenase-1 (HO-1) gene promoter modulates transcription of this enzyme which might have anti-inflammatory, anti-oxidant, anti-apoptotic and anti-proliferative effect. Croatian individuals, genotyped for the first time for (GT)n HO-1 polymorphism, had similar distribution of alleles and genotypes as observed in other European populations. Higher frequency of the short (S) alleles (GT less than 25) was observed in AAA patients (41.9% vs 28.2%, p=0.0026) compared to non-AAA individuals, due to the higher frequency of heterozygotes SL (54.7% vs 35.9%, p=0.0058), but not homozygotes SS (14.5% vs 10.3%, p=0.4376). SL genotype (L more than 25 GT), more often found in AAA individuals, appeared to increase risk for AAA (OR=1.72, 95% CI=1.20-2.81, p=0.009 ; after adjustment for age, sex, smoking, hypertension and hyperlipidemia: OR=1.53, 95% CI=0.90-3.09, p=0.062). Taking into consideration that our findings are contradictory to the results of the only one study performed so far on the association of (GT)n HO-1 polymorphism and AAA, further investigations are needed to clarify this relationship.