Genes, Genetics and Genetic Screening

Like anything in the scientific world, genetic screening is both praise and critiqued among the human population. Like many things, there are both pros and cons associated with the use of genetic testing. Genetic testing is the sequencing of human DNA in order to discover genetic differences, anomalies, or mutations that may prove pathological.

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Genetics by Kevin Simmons

One of the first important questions that arise while exploring genetic screening is,  what  do genes even tell us? Genes are the bits of DNA that give our cells their marching orders. They make up who we are at our most basic cellular level. The millions upon millions of cells we are born with play a very important role in our over all health. Our bodies are completely ran by our genes. We inherit each of our genes directly from our parents.  Two copies of each gene are passed on from each of our parents to us. Most genes are exactly the same from person to person, but in some instances, less than 1%, there are slight differences in the gene. This is called a gene mutation. A mutation is a permanent alteration in a gene that makes one of your genes different from the same gene in most other people. Some mutations only effect one gene, while others effect multiple. Gene mutations can impact the way our bodies work and survive in many ways.

Mutations can have three different effects. They may:

  • be neutral and have no effect
  • improve a protein and be beneficial
  • result in a protein that doesn’t work, which may cause disease

This is not to say that all mutations are harmful, because that is not the case. There are mutated genes that are unharmful, like the blue eye gene. “Originally, we all had brown eyes,” said Professor Hans Eiberg from the Department of Cellular and Molecular Medicine. “But a genetic mutation affecting the OCA2 gene in our chromosomes resulted in the creation of a “switch,” which literally “turned off” the ability to produce brown eyes.” The OCA2 gene codes for the so-called P protein, which is involved in the production of melanin, the pigment that gives colour to our hair, eyes and skin. The “switch,” which is located in the gene adjacent to OCA2 does not, however, turn off the gene entirely, but rather limits its action to reducing the production of melanin in the iris — effectively “diluting” brown eyes to blue.“Originally, we all had brown eyes,” – Professor Hans Eiberg from the Department of Cellular and Molecular Medicine. “But a genetic mutation affecting the OCA2 gene in our chromosomes resulted in the creation of a “switch,” which literally “turned off” the ability to produce brown eyes.” The OCA2 gene codes for the so-called P protein, which is involved in the production of melanin, the pigment that gives colour to our hair, eyes and skin. The “switch,” which is located in the gene adjacent to OCA2 does not, however, turn off the gene entirely, but rather limits its action to reducing the production of melanin in the iris — effectively “diluting” brown eyes to blue.” As this example shows, having the blue eye mutation is NOT harmful like other genetic mutations can be.

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Cells by RichelieuMatignon

A gene that no longer makes a protein the body needs combined with other factors can lead to diseases like breast or ovarian cancer, these are harmful mutations. Mutations come in two variations: inherited and acquired. Inherited mutations are passed on from one of your parents and they’re present in virtually all your cells. Mutations that occur because of overexposure to the sun or something going haywire during cell division are called acquired mutations.

So where does genetic screening come into play? Like we discussed earlier in the post, genetic testing is a type of medical test that identifies changes in chromosomes, genes, or proteins. The results of a genetic test can confirm or rule out a suspected genetic condition or help determine a person’s chance of developing or passing on a genetic disorder.

Several methods can be used for genetic testing:

  • Molecular genetic tests (or gene tests) study single genes or short lengths of DNA to identify variations or mutations that lead to a genetic disorder.
  • Chromosomal genetic tests analyze whole chromosomes or long lengths of DNA to see if there are large genetic changes, such as an extra copy of a chromosome, that cause a genetic condition.
  • Biochemical genetic tests study the amount or activity level of proteins; abnormalities in either can indicate changes to the DNA that result in a genetic disorder.

Genetic tests are performed on a sample of blood, hair, skin, amniotic fluid (the fluid that surrounds a fetus during pregnancy), or other tissue. The sample is sent to a laboratory where technicians look for specific changes in chromosomes, DNA, or proteins, depending on the suspected disorder. The laboratory reports the test results in writing to a person’s doctor or genetic counselor, or directly to the patient if requested. New born babies tests are done on a small blood sample, which is taken by pricking the baby’s heel. Unlike other types of genetic testing, a parent will usually only receive the result if it is positive. If the test result is positive, additional testing is needed to determine whether the baby has a genetic disorder.

Some benefits of genetic screening are, a positive result can direct a person toward available prevention, monitoring, and treatment options. Some test results can also help people make decisions about whether they want to have children or not. Infant and newborn screening can identify genetic disorders early in life so treatment can be started as early as possible.

Some risks and limitations of genetic screening involve the emotional, social, or financial consequences of the test results.  In many ways, having the genetic screening done can put a strain on relationships, leading people to feel angry and or depressed, and a lot of other factors on the emotional level.  As for limitations, genetic testing can provide only limited information about an inherited condition. Often times a test can’t determine if a person will show symptoms of a disorder, how severe the symptoms will be, or whether the disorder will progress over time. Another major limitation is the lack of treatment strategies for many genetic disorders once they are diagnosed.

There are many pros and cons when it comes to genetic screening. A large part of genetic screening is being ready for it and being ready for any outcomes that may arise. For many there are good outcomes but there are also many instances where outcomes aren’t what people expected. There are numerous different resources available for people thinking about genetic screening such as counselors, peer support groups and blogs.

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2 thoughts on “Genes, Genetics and Genetic Screening

  1. This is a great blog! I never realized that blue eyes were from a mutation specifically. I also think that genetic testing is great but definitely adds stress and complications emotionally, especially if the person finds out that they have a high probability of developing a condition but that there is really nothing they can do to prevent or cure it. Sometimes not knowing may be better.

    Liked by 1 person

  2. I love that you wrote about this! Genetic screening is poorly understood by many. I really like the question that you began with: “What do genes even tell us?” What do we do with the information from genetic screens? Excellent questions! While it may be helpful to couples trying to make decisions about whether to have children, it can also raise issues with possible insurance company abuses. So much to think about!

    Like

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