The Purebred Dexter Cattle Association of North America
About Lethal Genes
Lethal genes exist in every breed of cattle:
Neurophathic Hydrocephalus and Arthrogryposis Multiplex are lethal genetic defect that affects Angus and Angus-influenced cattle, Tibial Hemimelia is found in Shorthorns and Maine-Anjous. Beta (ß)-Mannosidosis in Salers, Contracture in Holstiens, Hypotrichosis congenita (Hairless) in Holsteins, Fresians and Jerseys and the list goes on. Chondro and PHA are the two biggies in the Dexter breed.
Lethal genes typically cause birth defects which results in the death of the fetus or newborn calf but in some cases the resulting deformaties can mean death for the dam as well.
But nowadays a lethal outcome is entirely preventable by using genetic testing to identify a carrier, having a clear understanding of inheritability and using both to make wise breed pairings.