Phenotype: Cholesterol deficiency (CD) affects lipid metabolism and causes young calves to die, usually within 3 weeks to 6 months of age, as a consequence of chronic diarrhea and failure to thrive. Affected calves show very low levels of cholesterol (severe hypocholesterolemia).
Mode of Inheritance: Autosomal recessive
Alleles: N = Normal/Unaffected, CD = Cholesterol deficiency
Breeds appropriate for testing: Holstein, Holstein crosses
Explanation of Results:
Cattle with N/N genotype will not be affected by cholesterol deficiency. They cannot transmit this cholesterol deficiency variant to their offspring.
Cattle with N/CD genotype are not expected to show clinical signs of cholesterol deficiency, but are carriers. They will transmit this cholesterol deficiency variant to 50% of their offspring. Matings between two carriers result in a 25% chance of producing a calf with cholesterol deficiency.
Cattle with CD/CD genotype will be affected by cholesterol deficiency, a lethal condition.
At least 15 business days; may be delayed beyond 15 business days if sample requires additional testing, or a new sample is requested.
Cholesterol deficiency (CD) is a recessive genetic disorder in Holstein cattle that affects lipid metabolism and causes young calves to die, usually within 3 weeks to 6 months of age, as a consequence of chronic diarrhea and failure to thrive. Affected calves show very low levels of cholesterol (severe hypocholesterolemia). The genetic defect traces back to bull Maughlin Storm born in 1991.
Molecular analyses identified the mutation responsible for CD as a 1.3Kb insertion of a transposable LTR element (ERV2-1) in the coding sequence of the apolipoprotein B (APOB) gene that renders the APOB protein non-functional. The APOB protein is a key component in a system responsible for transporting fat molecules, including cholesterol, around the body and into cells. Carriers of CD appear to be normal and show no clinical signs of malabsorption despite a reduced level of cholesterol when compared to non-carriers. A DNA diagnostic test for the APOB mutation has been developed by researchers in Switzerland to determine whether animals are free of the mutation, are CD-carriers (1 copy of the mutation) or CD-affected (2 copies of the mutation).
Breeders can use results from this test from the VGL, which is specific for the Holstein CD mutation, as a tool for selection of mating pairs to avoid producing affected calves.
Note: This test is specific for the mutation in the apolipoprotein B (APOB) gene associated with cholesterol deficiency in Holstein cattle.
Other Holstein breed-specific tests offered by the VGL:
Carrier. Animal has 1 copy of the CD mutation. Breeding to another carrier will produce 25% affected calves.
Affected. Animal has 2 copies of the CD-mutation.
Menzi, F., Besuchet‐Schmutz, N., Fragnière, M., Hofstetter, S., Jagannathan, V., Mock, T., Raemy, A., Studer, E., Mehinagic, K., Regenscheit, N., Meylan, M., Schmitz‐Hsu, F., & Drögemüller, C. (2016). A transposable element insertion in APOB causes cholesterol deficiency in Holstein cattle. Animal Genetics, 47(2), 253-257. doi: 10.1111/age.12410