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Mycobacterium avium complex sensitivity (MAC) - Miniature Schnauzer Type
| Acronym: | MAC |
| Gene: | |
| Mutation: | |
| Inheritance: | Autosomal Recessive |
| Sample type: | CHS (Cheek Swab), WBE (Whole Blood EDTA) |
Genetics and characteristics
Mycobacterium avium complex sensitivity (MAC) is a genetic condition characterized by increased susceptibility to severe forms of various types of mycobacterial infections. Mycobacterium is a larger group of bacteria that can cause infections in humans and other animals including dogs. The dog breed that is the most at risk is Miniature Schnauzer due to a mutation that affects their ability to defend against the bacteria and in most cases, the infection develops with inflammation localized mainly to the lungs, skin, kidneys, bone marrow, and/or digestive system and associated lymph nodes. The condition usually presents in dogs aged anywhere between ten months and three years of age and it usually starts to manifest as weight loss, lethargy, and generalized lymph node enlargement. The cause of MAC sensitivity is a mutation within the CARD9 gene that encodes a multi-functional signaling protein and is essential in autonomous innate host defense against a variety of fungal and bacterial species.
MAC sensitivity in Miniature Schnauzer dogs is inherited as an autosomal recessive trait, requiring two copies of the mutated CARD9 gene for the disease to develop. Dogs with only one copy of the mutated gene will not develop the disease but may act as carriers and pass the mutation to their offspring. Since the disease may have severe consequences, early detection by genetic testing is crucial for helping breeders in selecting future mating pairs and preventing the passing of the mutation to the offspring.
Results Reported As
Test Result |
Interpretation of test result |
CLEAR |
Tested mutation was not detected in animal with „clear“ result. Animal tested as clear has wild-type allele in homozygous state (i.e. two pairs of healthy alleles). It will not develop disease caused by tested mutation.* It will pass only wild-type allele to its offspring. |
CARRIER |
Tested mutation was detected in animal with „carrier“ result. Animal tested as carrier has one wild-type and one mutation allele, it is in heterozygous state. It will not develop disease caused by tested mutation.* It can pass wild-type or mutation allele to its offspring. |
AFFECTED |
Tested mutation was detected in animal with „affected“ result. Animal tested as affected has two copies of mutation alleles affecting the gene. It is likely the animal will experience a genetic disorder due to this mutation.** It will pass only mutation allele to its offspring. |
*Test excludes only tested mutation but not possible unknown mutations or factors that can lead to similar condition/symptoms.
** Potential unknown mutations or multiple other factors can possibly affect the likelihood of experiencing a genetic disorder.
References:
Ghielmetti, G., Giger, U. (2020). Mycobacterium avium: an Emerging Pathogen for Dog Breeds with Hereditary Immunodeficiencies. Current clinical microbiology reports, 7(3), 67–80. https://doi.org/10.1007/s40588-020-00145-5
Horn, B., Forshaw, D., Cousins, D., Irwin, P. J. (2000). Disseminated Mycobacterium avium infection in a dog with chronic diarrhoea. Australian veterinary journal, 78(5), 320–325. https://doi.org/10.1111/j.1751-0813.2000.tb11781.x