Intestinal Cobalamin Malabsorption (Giant Schnauzer Type)
Affected Genes: AMN
Inheritance: Autosomal Recessive
Variant(canFam6):
chr8:70319714-70319746: 33 bp deletion CGGGCTGCTGCTGCTGCTGCTGGCGCTGGCGGC
Breed: Giant Schnauzer
General Information: Intestinal cobalamin malabsorption (giant schnauzer type) is an inherited disease in dogs affecting their ability to absorb vitamin B12, leading to symptoms such as anorexia, lethargy, poor weight gain, and muscle weakness starting as early as 6 to 12 weeks of age. In severe cases, affected dogs may develop hepatic encephalopathy, a neurological condition potentially leading to seizures, coma, and death. Diagnostic markers include elevated methylmalonic acid levels and increased urinary proteins indicating cobalamin deficiency, alongside anemia and reduced neutrophil counts due to impaired blood cell production. Lifelong cobalamin supplementation is necessary, with most dogs responding well to treatment, though they may continue to excrete excess urinary proteins despite therapy.
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 of the AMN gene can identify carriers of intestinal cobalamin malabsorption (giant schnauzer type) in dogs, inherited in an autosomal recessive manner. Carrier dogs typically do not show signs of the disease but breeding two carriers increases the risk of producing affected offspring, with each pup having a 25% chance of inheriting two copies of the mutation. It's crucial to use reliable genetic testing in breeding practices to prevent passing on this condition, recommending against breeding known carriers together to avoid producing affected pups. Dogs without the mutation do not face an increased risk of having affected offspring.
References:
Fyfe JC, Jezyk PF, Giger U, Patterson DF. Inherited Selective Malabsorption of Vitamin B12 in Giant Schnauzers. J Am Anim Hosp Assoc. 1989;25:533–539.
He Q, Madsen M, Kilkenney A, Gregory B, Christensen EI, Vorum H, Hojrup P, Schaffer AA, Kirkness EF, Tanner SM, de la Chapelle A, Giger U, Moestrup SK, Fyfe JC. Amnionless function is required for cubilin brush-border expression and intrinsic factor-cobalamin (vitamin B12) absorption in vivo. Blood 2005 106(4):1447-1453.