Figure 6. The results of genetic linkage mapping using central retinal avascular area as the phenotype. A: Linkage map of avascular area across the whole genome created using no covariates (blue) and using weight, paternal grandmother, and sex as additive covariates in the analysis (red). Empirically derived genome-wide (alpha=0.05) thresholds of significance are shown as horizontal lines. For mapping without covariates the threshold of significance was a logarithm of odds (LOD) score of 3.75. For mapping with covariates the threshold of significance LOD score of 3.81. Mapping without covariates identified peaks on chromosomes 7 (LOD=8.90) and 9 (LOD=3.75). Mapping with covariates identifed a peak on chromosome 7 (LOD=9.83). B: Linkage map of avascular area across chromosome 9 created without inclusion of covariates, showing a peak at SNP rs4135590 (LOD=3.75, p=0.05). C: Effect plots of primary peak on chromosome 9. The BALB/cByJ allelotype was found to be additively protective against the development of OIR. D: Linkage map of avascular area across chromosome 7 created by including weight, paternal grandmother, and sex as additive covariates, showing a peak between SNPs rs13479506 and CEL-7_115892950 (LOD=9.83, p<0.004). E: Effect plot of the peak on chromosome 7 at the nearest marker, CEL-7_115892950. The BALB/cByJ allelotype at this locus is shown to have a protective effect in a recessive manner.