Title : Developing a genetic risk index for peanut allergy
Over 200 single nucleotide polymorphisms (SNPs) have been found to be associated with food allergy (FA) in genome-wide association studies (GWAS). A Genetic risk score (GRS), is an index that can be derived from genome-wide association studies to summarize the genetic risk encompassed by a set of SNPs, and is useful in risk stratification and prediction. Our objective was to use information from the Canadian Peanut Allergy Registry (CanPAR) GWAS study  to develop a GRS and evaluate the positive predictive value of the GRS in CanPAR and the Canadian Asthma Primary Prevention Study (CAPPS).
Methods :Our study aims to use the food allergy (FA)-associated SNPs using p-value thresholds ranging from 1.0 * 10-4 to 1.0 * 10-6 to generate a GRS using a weighted sum of the number of risk alleles (with values 0/1/2). Weighting each SNP by the natural log of their respective odds ratio (OR). We then evaluated the area under the curve (AUC) which is used to determine the effectiveness of the classification and the positive predictive value (PPV). The AUC value ranges from .5 to 1 with .5 being a poor classifier and 1 a perfect fit.
Conclusions: We have demonstrated that with 336 SNPs we can achieve an AUC of .80, a threshold used for biomarkers. However, for medical diagnosis and treatment an AUC of .95 is desired. We are currently working to identify the p-value threshold and number of SNPs necessary to reach an AUC of .95.