Genetics 101: The Basics of Genetics

“Our bodies are made of millions and millions of cells. We have skin cells, blood cells and nerve cells, bone cells and many, many different types of cells.

Inside the cell is an organelle called the nucleus. This is where most of our DNA is housed. When you look at the nucleus under the microscope, the picture is like a big plate of spaghetti; all mixed up. In the lab, the scientists can sort out this ‘messy’ picture, so it makes sense. The string like structures, or noodles, are called chromosomes  they come in pairs. One complete set comes from our mother in the egg and another from our father in the sperm.

Along the chromosomes lie our genes. We have about 20,000 genes in total. A gene is like a code or recipe for something that our body needs, like a protein or an enzyme. Most genes come in pairs, too. Problems can arise if there is a disease-causing variation in one or both copies of a particular gene.” 

My name is Matt Burgess and I am a board-certified genetic counselor. I work at Baylor Genetics as a Clinical Science Liaison, which means I collaborate with sales, genetic counselors, and lab directors to support education and company growth.  

In previous roles, where I worked clinically seeing patients, the quote above is how I would describe genetics to someone at the start of a consultation. The purpose of the statement was for my patients to understand the basics of genetics. Once the basics were covered, I would then lead a more specific discussion for my patient’s case. 

It wasn’t that long ago in medicine when genetics was an optional extra or on the fringes of clinical care. Whereas now, clinical genetics is an integral and essential part of many areas of medicine including pediatrics, cancer, neurology, cardiology, psychiatry, and obstetrics  to name just a few. 

As clinical genetics in a medical setting has grown and evolved, so has other areas of genetics. A few examples include forensic DNA in courts and legal settings to more fun or recreational products, like ancestry testing or genetic tests that determine a specific diet or exercise regime for the consumer.  

At Baylor Genetics, we are a clinical reference laboratory. This means all tests, we offer thousands of health-related medical tests, must be ordered by a medical professional and the results of the tests are issued to the requesting provider. 

Are you thinking about ordering a test for a patient? Or, is your healthcare provider ordering a test for you or loved one? Below are some common terms to know in the genetic testing industry: 

  • Allele: One or more variations of a gene. Everyone inherits two alleles of most genes (one from each parent). If both alleles are the same, the person is homozygous for that gene. If both are different, the person is heterozygous for that gene.  Alleles of a gene are like flavors of a cake. It’s true that your mom might give you a chocolate cake and dad might give you a caramel cheesecake, but there are still hundreds of different types of cakes out there.
  • Carrier: An individual that has one working and one non-working copy of a gene that is associated with a disease, which they can pass on. The person may or may not know that they are a carrier.
  • ChromosomeAn organized batch of DNA found inside the nucleus of a cell. Individuals have 23 pairs of chromosomes. 
  • DNA: The molecule that is the carrier of genetic information. It is made of two strands that form a double helix. 
  • Gene: unit that is passed on from a parent to offspring and help determine specific traits.
  • Genetic Counselor: People who have a specialized education in genetics and counseling. Their main role is to interpret tests, convey information to patients or physicians, and help families adapt to their disease. 
  • Heterozygous: When an individual inherits different forms of a gene from each parent. 
  • Homozygous: When an individual inherits identical forms of a gene from each parent.
  • Phenotype: person’s visible, physical, or biological traits (e.g. eye color, blood type, observable disease symptoms [for example, breast cancer], etc.). 
  • Genotype: person’s actual genetic code or make up.  person may have a breast cancer phenotype and BRCA mutation which forms their genotype 

Throughout my career, many people have told me that it is an exciting time to be in genetics. I think now, in this moment in time, this is particularly true. Testing is getting faster, cheaper, and more comprehensive.  

In the past, testing may have provided a diagnosis, but not much in the way of options. Now more and more, a diagnosis comes with an intervention or treatment, whether it is medication or surgical options. So, watch this space. Things are changing rapidly. Who knows how genetics and genomics will be able to help us even more in the not too distant future.  

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