Beta-casein A2*
Beta-casein is a naturally produced protein in cows’ milk which comes in two variants, A1 and A2. Genomnz™ can detect whether an animal carries the A2 beta-casein variant.
The beta-casein family constitutes up to 45% of the casein of bovine milk and is quite complex. In addition to A1 and A2, a number of related, but rarer, sub variants have been published to date including A3, B, C, D, E, F, G, H1, H2 and I. There may also be other types that have not yet been discovered/reported.
Test Results
Research has identified a mutation or SNP (single nucleotide polymorphism) in the bovine DNA sequence that distinguishes the A1 and A2 protein variants. When animals have an adenine (A) nucleotide at position 200 of the Beta-casein gene the protein type is A1 or B, and when they have a cytosine (C) nucleotide, the protein type is A2 or (rarely) A3.
The test identifies three classes of animal:
A2/A2
Where the beta-casein genotype is CC the animal will produce milk with an A2 or (rarely) A3 protein type
A1/A1
Where the genotype is AA the animal will produce milk with an A1 or B protein type.
A1/A2
Where the genotype is AC the animal has one allele of each type and will produce milk with a mixture of protein types.
While this test is adequate for selecting a herd of cows, which will produce >95% A2 milk, it does not discount the presence of the rare beta-casein genotypes.
* Genomnz™ does not endorse any claims related to A2 milk.
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Bovine leukocyte adhesion deficiency (BLAD)
BLAD is a genetic defect affecting white blood cell function which causes extreme susceptibility to infection. Genomnz™ can test for the mutation in the CD18 gene that causes leukocyte adhesion deficiency in Holstein cattle.
Bovine leukocyte adhesion deficiency (BLAD) is a recessive disease and results in an affected animal's white blood cells failing to attach to the cells lining the blood vessels, an essential step in their migration to the point of infection to destroy invading pathogens. Affected calves suffer from recurrent bacterial infections of the respiratory and gastrointestinal tracts and eventually succumb to infection.
Test Results
Research has identified the specific DNA code that causes BLAD in Holstein cattle. BLAD carriers have a mutation or SNP (single nucleotide polymorphism) in the DNA sequence changing an adenine (A) nucleotide to a guanine (G) nucleotide at position 383 of the CD18 gene.
The test identifies three classes of animal:
Normal (non-carrier)
Where the CD18 genotype is AA the animal does not have the disease.
Carrier
Where the genotype is AG the animal has one copy of the mutated gene and one copy of the normal gene so although it may not show signs of the disease it will pass the mutation on to about half its offspring.
Affected
Where the genotype is GG the animal will be affected by BLAD, show clinical symptoms, and will die at an early age.
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Complex vertebral malformation (CVM)
CVM is a genetic defect that causes aborted foetuses and stillborn calves. Genomnz™ can identify bovine carriers of CVM by testing for a specific mutation in the SLC35A3 gene.
Complex vertebral malformation (CVM) is a recessive disease and most affected animals are either aborted as foetuses during gestation, born prematurely, or stillborn. The defect is characterised by reduced weight and multiple deformities including a misshapen backbone, tendon contractions in the legs and heart malformations.
Test Results
Research has identified the specific DNA code that causes CVM in Holstein-Friesian cattle. CVM carriers have a mutation or SNP (single nucleotide polymorphism) in the DNA sequence changing a guanine (G) nucleotide to a thymine (T) nucleotide at position 559 of the SLC35A3 gene.
The test identifies three classes of animal:
Normal (non-carrier)
Where the SLC35A3 genotype is GG the animal does not have the disease.
Carrier
Where the genotype is GT the animal has one copy of the mutated gene and one copy of the normal gene so although it may not show signs of the disease it will pass the mutation on to about half its offspring.
Affected
Where the genotype is TT the animal will be affected by CVM and will not survive.
The CVM test technology is licensed from The Danish Institute of Agricultural Sciences.
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Factor XI (FXI)
FXI is a deficiency of blood coagulation Factor XI. Genomnz™ can test for the mutation within the factor XI gene that causes the defect in Holstein cattle.
Factor XI (FXI) is a recessive deficiency of blood coagulation Factor XI and affected animals can be asymptomatic or exhibit a number of indicators including prolonged bleeding after injection, production of bloody milk and anaemia.
Test Results
Research has identified the specific DNA code that causes FXI in Holstein cattle. FXI deficient animals have an extra 76 base pair segment of DNA inserted into the Factor XI gene. This mutation results in a FXI protein that can no longer function in the early activation phase of the blood clotting process.
The test identifies three classes of animal:
Normal (non-carrier)
Where there is no 76bp insertion, the animal does not have the deficiency.
Carrier
Where there is one copy of the insertion and one copy of the normal gene, an animal may show varying symptoms and degrees of reduced FXI activity and will pass the gene on to about half its offspring.
Affected
Where there are two copies of the 76bp insertion the animal will be FXI deficient and will pass the mutation on to its entire offspring.
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Coat Colour
Mutations in the melanocyte-stimulating hormone receptor (MSHR) are associated with cattle coat colour. Genomnz™ can identify whether a black animal is homozygous or heterozygous for black coat colour.
The basis of coat colour in cattle is the presence or absence of two types of melanins, eumelanin and phaeomelanin, in the hair. The melanocyte-stimulating hormone receptor (MSHR) has a major function in the regulation of black/brown (eumelanin) versus red/yellow (phaeomelanin) pigment synthesis.
Test Results
Research has identified three alleles at the MSHR locus which are responsible for most of the variation in cattle coat colour; ED, dominant black, E+, the wild-type allele responsible for most combinations of red or reddish brown and black; and e, recessive red. Black (ED) animals have a mutation or SNP (single nucleotide polymorphism) in the DNA sequence changing a thymine (T) nucleotide to a cytosine (C) nucleotide at position 296 of the MSHR gene.
The test identifies three classes of animal:
ED/ED (black)
Where the MSHR genotype is CC the animal will have a uniformly black coat colour.
ED/- (red-black)
Where the genotype is CT the animal will look black because ED is dominant over the other alleles however it is actually heterozygous for either the wild-type or recessive red allele (ED/E+ or ED/e).
e/- or E+/E+ (non-black)
Where the genotype is TT the animal could be reddish brown with varying amounts of black (E+/e or E+/E+) or red (e/e) depending which alleles are present.
A separate, Red Factor, test is necessary to distinguish carriers of the E+ (wild-type) or e (recessive red) alleles among black Holstein cattle. This method is currently being evaluated by the Genomnz™ laboratory and this test will be offered once validation is complete.
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For information about sample types and sampling instructions please see our sample types page. For information about submitting samples for single gene tests please see our sample submission page or download a submission form.