KDM2B-associated paunch calf syndrome in Marchigiana cattle

Background: Chianina, Romagnola, and Marchigiana are the 3 most important Italian breeds of cattle raised in the Apennine Mountains. Inherited disorders have been reported in the Chianina and Romagnola breeds but not in the Marchigiana breed. Recently, a case resembling recessively inherited KDM2B-associated paunch calf syndrome (PCS) in Romagnola cattle was identified in Marchigiana cattle. Hypothesis/Objectives: To characterize the features of the observed congenital anomaly, evaluate its possible genetic etiology, and determine the prevalence of the deleterious allele in the Marchigiana population. Animals: A single stillborn Marchigiana calf was referred for clinicopathological examination because of the presence of PCS-like morphological lesions. Methods: The animal was necropsied and the calf and its parents were genotyped. A PCR-based direct gene test was applied to determine the KDM2B genotype and 114 Marchigiana bulls were genotyped. Results: The pathological phenotype included facial deformities, enlarged fluid-filled abdomen, and hepatic fibrosis. The affected animal was the offspring of consanguineous mating and homozygous presence of the KDM2B missense variant was confirmed. Both parents were heterozygous for KDM2B and the prevalence of carriers in a selected population of Marchigiana bulls was <2%. Conclusions and Clinical Importance: The characteristic malformations and genetic findings were consistent with the diagnosis of PCS and provide evidence that the deleterious KDM2B variant initially detected in Romagnola cattle also occurs in the Marchigiana breed.