Neuroaxonal Dystrophy (Giant Schnauzer Type)
Affected Genes: MFN2
Inheritance: Autosomal Recessive
Variant(canFam6):
chr2:80822525-80822527: 3 bp deletion TCC
Breed: Giant Schnauzer
General Information: Neuroaxonal Dystrophy (NAD) in Giant Schnauzers is a devastating genetic condition that manifests as early as in utero, significantly impairing motor nerve cells and muscle function. Puppies affected with NAD are born with severe physical abnormalities including contracted joints, immobile limbs, curved spines, and notably underdeveloped lungs. These critical conditions result in the inability to breathe independently, leading to respiratory failure immediately after birth. The severity of these symptoms makes survival beyond birth virtually impossible, often necessitating humane euthanasia shortly after delivery to prevent suffering.
How to Read Your Dog's Test Results for this Genetic Variant:
Two Variants Detected: Dog Likely Affected
One Variant Detected: Dog Unlikely Affected
No Variants Detected: No Effect
Gene / Testing Information: Genetic testing for Neuroaxonal Dystrophy (NAD) in Giant Schnauzers focuses on the MFN2 gene, which can reveal whether a dog carries the genetic mutation responsible for this condition. NAD is passed on in an autosomal recessive manner, meaning that a puppy must inherit two copies of the defective gene—one from each parent—to suffer from the disorder. Carriers of one copy of the mutation do not show any symptoms but can transmit the gene to their offspring. Breeding strategies should involve genetic testing to identify carriers and avoid mating two carriers, which would result in a 25% chance of producing affected offspring per pregnancy. The use of genetic testing is crucial for breeders to make informed decisions that prevent the birth of affected puppies, ensuring healthier future generations. It is highly recommended to breed only non-carriers or carriers with non-carriers to eliminate this lethal mutation from the breeding lines.
References:
Fyfe JC, Al-Tamimi RA, Castellani RJ, Rosenstein D, Goldowitz D, Henthorn PS. Inherited neuroaxonal dystrophy in dogs causing lethal, fetal-onset motor system dysfunction and cerebellar hypoplasia. J Comp Neurol. 2010 518(18):3771-84.
Fyfe JC, Al-Tamimi RA, Liu J, Schäffer AA, Agarwala R, Henthorn PS. A novel mitofusin 2 mutation causes canine fetal-onset neuroaxonal dystrophy. 2011 Neurogenetics 12(3):223-232.