Haptoglobin genotype and outcome after spontaneous intracerebral haemorrhage

Isabel Charlotte Hostettler, Matthew J. Morton, Gareth Ambler, Nabila Kazmi, Tom R Gaunt, Duncan Wilson, Clare Shakeshaft, H R Jäger, Hannah Cohen, Tarek Yousry, Rustam Al-Shahi Salman, Gregory Y H Lip, Martin Brown, Keith W Muir, Henry Houlden, Diederik O Bulters, Ian Galea, David J Werring

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Abstract

Objective: Haptoglobin is a haemoglobin-scavenging protein that binds and neutralises free haemoglobin and modulates inflammation and endothelial progenitor cell function. A HP gene copy number variation (CNV) generates HP1 and HP2 alleles, while the single-nucleotide polymorphism rs2000999 influences their levels. The HP1 allele is hypothesised to improve outcome after spontaneous (non-traumatic) intracerebral haemorrhage (ICH). We investigated the associations of the HP CNV genotype and rs2000999 with haematoma volume, perihaematomal oedema (PHO) volume, functional outcome and mortality after ICH.

Methods: We included patients with neuroimaging-proven ICH, available DNA and 6-month follow-up in an observational cohort study (CROMIS-2). We classified patients into three groups according to the HP CNV: 1–1, 2–1 or 2–2 and also dichotomised HP into HP1-containing genotypes (HP1-1 and HP2-1) and HP2-2 to evaluate the HP1 allele. We measured ICH and PHO volume on CT; PHO was measured by oedema extension distance. Functional outcome was assessed by modified Rankin score (unfavourable outcome defined as mRS 3–6).

Results: We included 731 patients (mean age 73.4, 43.5% female). Distribution of HP CNV genotype was: HP1-1 n=132 (18.1%); HP2-1 n=342 (46.8%); and HP2-2 n=257 (35.2%). In the multivariable model mortality comparisons between HP groups, HP2-2 as reference, were as follows: OR HP1-1 0.73, 95% CI 0.34 to 1.56 (p value=0.41) and OR HP2-1 0.5, 95% CI 0.28 to 0.89 (p value=0.02) (overall p value=0.06). We found no evidence of association of HP CNV or rs200999 with functional outcome, ICH volume or PHO volume.

Conclusion: The HP2-1 genotype might be associated with lower 6-month mortality after ICH; this finding merits further study.
Original languageEnglish
Number of pages7
JournalJournal of Neurology, Neurosurgery, and Psychiatry
DOIs
Publication statusPublished - 10 Jan 2020

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