Congenital myasthenic syndrome of Brahman cattle in South Africa

A congenital myasthenic syndrome in Brahman cattle is caused by a homozygous 20 base pair deletion (470del20) in the gene coding for the epsilon subunit of the acetylcholine receptor at the neuromuscular junction. It causes a progressive muscle weakness starting either at birth or within the first month. A PCR‐based DNA test, using blood or semen stored on FTA paper, was developed and validated; the test makes it possible to differentiate rapidly and accurately between homozygous wild‐type, heterozygous and homozygous affected animals. Preliminary testing of Brahman cattle in South Africa has revealed several carrier animals, some of them influential animals in the breeding population.