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12 fascinating facts about DNA

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Subject: Facts about DNA that genetics labs may not tell you
Source: Homestead & Miniature Cattle Directory;
Author: Donna Grace Vickery,

Geneticists may not be able to say some of the things I claim as "facts" in this short article ... because the following list of "facts" about DNA could be disproven in rare, solitary cases. In fact, that is what a mutation itself is: a changed or broken sequence in DNA, which goes against the former rules or facts (that we call "wild type" in livestock genetics). In some cases, history, registries, breeding programs, profits and even livelihoods, were built on unclear understanding of genetics, before we knew more about them. For many reasons, what we have learned, is not openly discussed, for fear of blowback, therefore, many of us still do not hear much about today's known DNA "facts". This article is intended to set a foundation understanding about how DNA mutations work, and what they can tell us about the animals standing in front of us, and about that animal's ancestors. This information illustrates how mutations over decades and centuries provide reasonable doubt or proof of relationships between breeds, their origins, history and development.

  1. Genetic diseases in cattle are tissue specific viz; skeletal, central nervous system, blood, skin /hair, muscle or ophthalmic.

  2. Genetic disorders and diseases are caused by inherited mutatations; which are damaged genes or chromosomes.

  3. In 2016, there were 130 Mendelian traits with known causal mutations in 117 cattle genes. We find more every year.

  4. Genetic mutations do not all cause what we term disorders or disease (for example polled mutations).

  5. Genetic mutations are very common* and we believe multiple mutations probably exist in most or all living animals. The possibiliy of how many mutations may occur in any population over time, is practically infinite. Perhaps that is comparable to how many different places lightening can strike over time. It is said that lightening strikes earth about 8 million times per day.

  6. On the opposite end of the spectrum, is the probability of an exact same mutation happening more than once in the same breed or population of animals over time; which is practically nil. The possibility of that occuring would be considerably lower than the chance of lightening striking twice in the same spot. It might be more comparable to finding 2 unrelated people accused of a crime with identical fingerprints. If I really wanted to put it in perspective, I'd say the likelihood of the same exact mutation happening more than once in the same breed or population of animals over time would be the same chance as me winning the lottery.

  7. Iceland scientists found 40 mutations of the coronavirusFor all reasonable intents & purposes, if the exact same genetic mutation is found in 2 different animals of the same species, they are related. It is reasonable to assume, and to understand that 2 animals with the same exact mutation will both trace back to one single ancestor that the mutation occurred in, and was passed down from. That is why particular genetic mutations are found in breeds that share history, or only in specific breeds, or only in certain bloodlines, depending upon how long ago the mutation occurred and how far it has spread. It may have occured (or discovered) a year ago, or it may have occured somewhere in bovine history before domestication occured. This is how the development of breeds of animals can be documented. Mutations in the DNA of a virus is an example of tracing the spread of Cov19: Iceland scientists found 40 mutations of the coronavirus, report says...

  8. Many recessive genetic mutations are undesirable. Most of them are believed to probably (when inherited as homozygous) result in spontaneous abortions, or do not survive into breeding age animals. Undesirable mutations that are dominant or semi-dominant do not last long in a breed if the trait is something that mankind or nature selects against. Some mutations are surviveable over generations, or even benign. Occasionally a few are beneficial (to nature or mankind). Mutations, genetic drift, natural selection and migration, are some of the basic mechanisms of evolution, and help populations survive environmental changes, as well as develop breeds under selection pressure.

  9. Some genetic conditions are markers (closely linked) for economically important or desirable traits. Those can be the quickest to spread in a population. For example, desirable hair for club calves may result from alleles located close on the gene to the PHA disease mutation, which initially led to the increase of PHA among Maine Anjou influenced club calf cattle. There are many other examples of this in breeds of cattle.

  10. There can be a number of different mutations that result in the same identical disease. For example, there are several different mutations (probably at least a half dozen) that cause what we know as the bulldog chondrodysplasia form of dwarfism in cattle. We have isolated 9 known myostatin mutations that result in double muscling. And yes, if 2 animals test positive (to the same identical test) for the same bulldog calf, or double muscling mutation, then, those 2 animals are related.

  11. Each different mutation requires its own specific DNA test to identify it (even if the disease or condition they cause is identical).

  12. Genomic technology is ever-evolving. Before making any financial decisions, such as choosing a breed, or implementing a DNA testing program in your cattle herd, or signing up for all the DNA tests recommended by your registry, inform yourself. First, learn your livestock's heritage. Know what breeds and what bloodlines are in your animals' pedigrees. Check for the latest research news, lab tests, products and news. If you are not currently testing it may be prudent to collect DNA samples (e.g. tail hair) on important animals in your herd (e.g. A.I. sires, herd bulls, donor cows, or your best replacement lines of cows) and store them for potential future research.


* Dr. Kent Weigel, Professor & Chair, Dep't of Dairy Science, U of WI, Madison; Aug, 2011: "today we recognize that ...inherited conditions are not rare anomalies that occur once in a decade in a handful of genetically unfit animals. ...scientists now believe that it is likely that every individual carries several genes that, if expressed in homozygous form, would lead to a severely impaired or lethal phenotype"

Additional Reading:

DNA TESTS: Homestead & Miniature Cattle Directory of Heritable Diseases
What is the difference between "fullblood" and "purebred"?
BREEDS of Homestead & Miniature Cattle
What to KNOW ABOUT BREEDS of Homestead & Miniature Cattle
What to know about Breed REGISTRIES
How to Calculate Ancestor Blood Percentage ~ a tutorial using your registered animal's pedigree


AgriGenomics Mansfield, Illinois
Biogenetic Services, Brookings, South Dakota
Neogen, GeneSeek®, Igenity, SeekSire, Neogen Genomics®, Lansing Michigan
Genetic Visions, Middleton, Wisconsin
MMI Genomics, Davis, California
Pfizer Animal Genetics, Harahan, Louisiana
Reprotec, Tucson, Arizona
UC Davis Veterinary Genetics Lab (VGL), Davis, California
Zoetis Genetics (formerly Pfizer Animal Health), Kalamazoo, Michigan
The American Grey Steppe Cattle Association,
Veterinary Medicine (Eleventh Edition), 2017
Dr. Tony Knight, CSU) (2010)
Genetic Defects • • 2014-9
From Big to Small to Big to Small: A 3-part Pictorial History of Cattle Type Changes Over the Years, by Harlan Ritchie
and too many more to list...

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author: Donna Grace

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