A missense variant in DGKG as a recessive functional variant for hepatic fibrinogen storage disease in Wagyu cattle

Abstract

Hepatic fibrinogen storage disease (HFSD) was diagnosed in a 5‐month‐old Wagyu calf with a history of recurrent respiratory disease. It was characterized by lethargy, dehydration, acidemia, and increased liver enzyme activities. Histologically, disseminated hepatocytes were swollen and showed a single, sharply demarcated, faintly eosinophilic cytoplasmic inclusion with a ground‐glass appearance, with the nucleus in an eccentric position. Cytoplasmic inclusions did not stain with the periodic acid‐Schiff (PAS) reaction. Using a rabbit polyclonal antibody against fibrinogen, the cytoplasmic vacuoles in the hepatocytes stained intensely. Electron microscopy disclosed hepatocytes with membrane‐bound cytoplasmic inclusions filled with fine granular material interspersed with a few coarse‐grained electron‐dense granules. A trio whole‐genome sequencing approach identified a deleterious homozygous missense variant in DGKG (p.Thr721Ile). The allele frequency in 209 genotyped Wagyu was 7.2%. This is a report of a DGKG‐related recessive inherited disorder in cattle and adds DGKG to the list of candidate genes for HFSD in other species.