Using the Fisher's Exact Probability test, the genetic differentiation of SNP alleles and SNP genotype results revealed significant differences in SNP allele frequencies for the CTNS, IGF2R, GHR (Polish HF breed), IGF2BP3, GHR (Hereford breed) and IQGAP2 SNP loci (S58 Table). This evidence concerns the gene GHR and hydrops fetalis.