17p12 Influences Hematoma Volume and Outcome in Spontaneous Intracerebral Hemorrhage

Abstract

Background and purpose: Hematoma volume is an important determinant of clinical outcome in spontaneous intracerebral hemorrhage (ICH). We performed a genome-wide association study (GWAS) of hematoma volume with the aim of identifying novel biological pathways involved in the pathophysiology of primary brain injury in ICH.

Methods: We conducted a 2-stage (discovery and replication) case-only genome-wide association study in patients with ICH of European ancestry. We utilized the admission head computed tomography to calculate hematoma volume via semiautomated computer-assisted technique. After quality control and imputation, 7 million genetic variants were available for association testing with ICH volume, which was performed separately in lobar and nonlobar ICH cases using linear regression. Signals with P<5×10^-8 were pursued in replication and tested for association with admission Glasgow coma scale and 3-month post-ICH dichotomized (0-2 versus 3-6) modified Rankin Scale using ordinal and logistic regression, respectively.

Results: The discovery phase included 394 ICH cases (228 lobar and 166 nonlobar) and identified 2 susceptibility loci: a genomic region on 22q13 encompassing PARVB (top single-nucleotide polymorphism rs9614326: β, 1.84; SE, 0.32; P=4.4×10^-8) for lobar ICH volume and an intergenic region overlying numerous copy number variants on 17p12 (top single-nucleotide polymorphism rs11655160: β, 0.95; SE, 0.17; P=4.3×10^-8) for nonlobar ICH volume. The replication included 240 ICH cases (71 lobar and 169 nonlobar) and corroborated the association for 17p12 (P=0.04; meta-analysis P=2.5×10^-9; heterogeneity, P=0.16) but not for 22q13 (P=0.49). In multivariable analysis, rs11655160 was also associated with lower admission Glasgow coma scale (odds ratio, 0.17; P=0.004) and increased risk of poor 3-month modified Rankin Scale (odds ratio, 1.94; P=0.045).

Conclusions: We identified 17p12 as a novel susceptibility risk locus for hematoma volume, clinical severity, and functional outcome in nonlobar ICH. Replication in other ethnicities and follow-up translational studies are needed to elucidate the mechanism mediating the observed association.

Keywords: cerebral hemorrhage; genetics; genome-wide association study; humans; neuroimaging.

Figure 1

Genome-wide Association results of autosomal SNPs in with lobar ICH volume (A) and non-lobar ICH volume (B) The plots show –log10-transformed p values for genotyped and imputed SNPs with respect to their physical positions. The threshold for association at genome-wide significance (p=5×10⁻⁸) is shown by the upper line, and the lower line corresponds to p=5×10⁻⁵

Figure 2

Zoom Plots of the regional association results. (A) Chromosomal region 22q13.3 in lobar ICH. (B) Chromosomal region 17p12 in non-lobar ICH. The index-associated SNP is labeled in violet.