A nonsense mutation in PLD4 is perfectly associated with the disease phenotype. Genomic structure of bovine PLD4 (A). Grey boxes represent exons. The red box represents exon 6 including rs378824791, introducing a premature stop codon. Genomic and protein sequence of exon 6 of PLD4 (B). The affected codon (p.W215X, TGG → TGA) is highlighted with red colour.