Inheritance of congenital myasthenia gravis in smooth fox terrier dogs

: The phenotypes with respect to congenital myasthenia gravis of 132 smooth fox terrier dogs from 25 matings were analyzed. These included both prospective and retrospective matings. It was determined that congenital myasthenia gravis in the smooth fox terrier dog breed is inherited in an autosomal recessive manner with complete penetrance. We propose the symbol mg for the gene for congenital myasthenia gravis in the smooth fox terrier. Attempts to maintain live affected dogs to adulthood were unsuccessful and it is concluded that this is a lethal trait.