IGF2 and hydrops fetalis: We selected three SNPs that were uniquely expressed in only one cattle breed (CTNS and P4HA2 SNP gene loci specific to the Polish Red breed and IQGAP2 SNP gene locus specific to the Hereford breed), and the remaining six SNP gene loci that were specific to all the breeds (GHR, IGF2R, IGF2BP3, IGFBP4 SNP gene loci specific to the Polish HF breed, and GHR and IGF2 SNP gene loci specific to the Hereford breed, respectively).