36 Correlation between the Warrior/Worrier Gene on Post Burn Pruritus and Scarring

Abstract

Associations between genetic variation and clinical conditions suggest that single nucleotide polymorphisms (SNPs) correlate with post-burn outcomes. One candidate gene, catechol O methyl transferase (COMT), modulates catecholamine metabolism and has been associated with stress and pain tolerance. Whereas individuals with the wild type genotype (GG) demonstrate more effective stress response, persons with an AA polymorphism break down dopamine more slowly and are vulnerable to stress. The aim of this study was to determine whether the rs4680 SNP is associated with post-burn pruritus and scarring. We examined adult burn patients, admitted between 2007 and 2017, with deep partial thickness burns or delayed healing. Subjects provided blood samples for genotyping and self-reported itch scores (0 to 10) within 1 year of injury. Scarring was measured using the Vancouver Scar Scale (VSS). Itch scores 4 and above and VSS scores over 7 were considered severe. Genomic DNA was genotyped for the rs4680 SNP using realtime PCR. Data were analyzed using ANOVA and multivariate logistic regression. Sufficient clinical data was available for 639 subjects. Our analyses corroborates previous reports that burn size ≥20% TBSA and Asian, Native American/Alaskan Indian race are significant risk factors for both severe pruritus and scarring and African American race are risk factors for itch. Severity of scarring and itch decreased with the SNP rs4680 AA variant. Mean itch and VSS scores were highest for GG homozygotes and lowest for AA homozygotes; heterozygote scores were between the two extremes. This relationship was statistically significant for VSS score (p=0.05) but not for itch (p=0.41). Multivariate logistic regression did not identify rs4680 genotype as a significant factor for either scarring or itch. Although our analysis identifies a trend between COMT genotype and both itch and scarring, rs4680 genetic variation does not appear to constitute an independent risk factor. Understanding genetic determinants of wound healing will ultimately allow clinicians to predict and potentially prevent severe pruritus and scarring.