Introduction: Although family history studies in ischemic stroke support that genetic factors may be involved in the pathogenesis of two major subtypes of ischemia stroke: large-artery atherosclerosis (LAA) and small-vessel occlusion (SVO), it is still unclear which particular genetic factors contribute to LAA or SVO.
Hypothesis: Because the etiology of ischemic stroke is heterogeneous, we hypothesize that genetic factors may vary by etiologic subtypes or ethnicities. Thus, we aim to identify genetic factors that contribute to LAA or SVO based on two independent Han Chinese populations.
Methods: Novel genetic variants that predispose individuals to LAA and SVO were identified by genome-wide association study comprising of 824 individuals (including 444 LAA cases and 380 SVO cases) and 1,727 controls in a Han Chinese population residing in Taiwan. The LAA study was replicated in an independent Han Chinese population comprising of an additional 319 LAA cases and 1,802 controls.
Results: In LAA cases, from two independent populations, we identified five single-nucleotide polymorphisms (SNPs), including SNP-1 (P = 3.10 х 10–8), SNP-2 (P = 4.00 х 10–9), SNP-3 (P = 3.57 х 10–8), SNP-4 (P = 1.76 х 10–8), and SNP-5 (P = 2.92 х 10–8), at one novel locus on chromosome 14q13.3 within PTCSC3 (encoding papillary thyroid carcinoma susceptibility candidate 3). In SVO cases, from the discovery stage, we identified two novel candidate susceptibility loci on chromosome 3p25.3 (SNP-6, P = 3.24 х 10–5) and chromosome 14 q31.1 (SNP-7, P = 2.58 х 10–4).
Conclusions: For LAA, the newly identified SNPs within PTCSC3 gene were found to have genome-wide statistical significance (P < 5 х 10–8) and were shown to be located in a risk locus correlated with papillary thyroid carcinoma. Moreover, the genetic association between PTCSC3 gene and SVO was not identified, which suggested that PTCSC3 is a specific susceptibility locus for LAA. For SVO, we identified two novel candidate genetic loci which were valuable for replication by an independent population with SVO. In conclusion, our findings provide insights into the genetic basis of LAA and SVO, which may be applicable in the study of the pathogenesis of ischemic stroke and in the development of alternative therapeutic interventions.