BackgroundIschemic injury is a common mechanism in both ischemic stroke (IS) and acute coronary syndrome (ACS). Matrix metalloproteinase 9 (MMP-9), an endopeptidase that degrades extracellular matrix, is important in the pathogenesis of IS. The purpose of this study is to evaluate the association between the SNP rs17576 in MMP-9 gene with (1) the risk and severity of acute ischemic stroke in Saudi Arab individuals with recent acute coronary syndrome, and (2) the risk of acute coronary syndrome in Saudi Arab individuals without ischemic stroke. MethodsA case control study of 200 IS patients, 520 ACS patients (without IS), and 500 aged-matched healthy controls were genotyped to detect the MMP-9 polymorphism rs17156. ResultsOur study demonstrated a non-significant difference in the genotype and allele frequencies of the MMP9 rs17576 polymorphism between the patients with IS and patients with ACS without IS (P = 0.31 for the GA genotype, 0.25 for the AA genotype and P = 0.20 for the A allele). AA genotype was found to be statistically significant between IS and control groups; [OR=1.84, 95 % CI (1.08-3.14), p =0.015]. A allele showed a significant difference between the two groups [OR=1.28, 95 % CI (1.00-1.64), p =0.028]. By comparing ACS without IS and controls, AA genotype was significant [OR=1.46, 95 % CI (1.01–2.12), p =0.029]. Stratification by NIHSS score revealed higher mortality and early neurologic deterioration in IS patients with NIHSS score ≥ 16 (p < 0.001, 0.044 respectively). ConclusionWe deduced the lack of association either with allele or genotype frequencies (p>0.05) between the IS cases and the cases of ACS without IS. In contrast there was a significant association of mutant genotype AA between either the IS group or ACS (without IS) group, and the control group. In addition, different rs17576 genotypes were not associated with raised mortality or a tendency to develop early neurologic deterioration.