Fig. 4

Regional association plot of the region (on ECA1) most significantly associated with hydrocephalus in Friesian horses. Significance level based on genotype differences between cases (n = 13) and controls (n = 69) using a χ ²-test (2df). The horizontal line is the genome-wide Bonferroni corrected significance level (P = 1.68 × 10⁻⁶). Location of the B3GALNT2 gene [Ensembl:ENSECAG00000013338] is indicated by the black cross. SNPs surrounding B3GALNT2 are coloured in diminishing red to reflect LD (pair-wise r ² values) between the candidate mutation in B3GALNT2 and SNPs. LD calculations between the mutation and the surrounding SNPs are based on genotypes for the mutation of 13 cases, 45 controls and 3 dams of cases and on SNP genotypes of all 13 cases and 69 controls