Monozygotic origin of bovine and buffalo calves with diprosopia or dicephalia

Congenital malformations, including cephalic anomalies such as diprosopia and dicephalia, represent rare but significant developmental abnormalities in humans and animals. While these conditions are primarily attributed to incomplete embryonic splitting, their genetic origins in domestic animals remain poorly understood. This study presents a detailed molecular and anatomical investigation of three cases of cephalic malformations in ruminants: two Holstein-Friesian calves and one Mediterranean Italian River Buffalo. Anatomical analyses classified the malformations as diprosopus in two cases and dicephalic in one. Notably, this is the first reported case of dicephalia in a female Mediterranean Italian River Buffalo. Molecular analysis using microsatellite markers and sex-linked genes (AMELX/Y and SRY) confirmed the monozygotic origin and the female sex of all cases, with identical genotypes detected in both heads of each calf.