Basics of Genetics

The human body is a very complex system of cells that must work together. Each of your cells contains DNA, and specific DNA sequences spell out different genes. So, what is the purpose of all of this genetic data? Genes act as the code that controls all of the functions of your body, including how you look, act, and feel. The information contained in your genes tells your body how to run properly.

What Makes Up a Gene?

Let’s start with the basics. Your entire body follows instructions that are found in your DNA. DNA is made up of 4 different molecules, referred to as bases - Adenine, Thymine, Cytosine, and Guanine. These four bases are commonly referred to by their first letter: A, T, C, and G. There are about three billion of these bases inside your body. When put into different combinations, these sequences spell out different genes; your genes vary widely in their length, with some genes containing a few hundred bases while others contain millions. Genes act as the instruction manual for building all the proteins that your body needs to survive. These proteins perform vital functions in the cells of your body, ensuring proper structure, function, and regulation of cellular structures.

Everyone has variations in their genes that make them unique; however, you may be surprised to hear that 99% of the genes in your body are the same as the genes everyone else has. In the other 1% of genes, different alleles allow for some genetic differences between people. An allele is a version of a gene. One gene can have multiple alleles, which have slight differences in their DNA sequences. For example, let’s say a certain gene determines eye color. One allele of this gene may cause green eyes, while another may cause brown eyes.

SNP (Single Nucleotide Polymorphism)

One type of genetic variation is a SNP, or single nucleotide polymorphism. This is simply when a single DNA base is switched for another base, causing a slight change in the genetic code which can in turn cause a change in the way you express a trait. SNPs are the most common form of genetic variation in humans. Scientists estimate that people have between 4 and 5 million SNPs in their genome. Most of the time, SNPs have no effect on someone’s health. However, some of these DNA changes can tell researchers important information such as how at risk someone is for a certain disease, or how they may respond to a particular medication.

Haplotypes

Some genes have more complex types of variations, called haplotypes. A haplotype can be a group of alleles or a group of SNPs that are commonly inherited together because they are found on the same chromosome. A chromosome is a molecular structure that packages your DNA. Haplotypes typically occur when variations are very close together on a chromosome, making it unlikely that one of the SNPs or alleles would be inherited without the other. The most well-known gene this applies to is APOE, which has been linked with Alzheimer’s and several other diseases and conditions.

How do We Get Our Genes?

You inherited your genes from your biological mother and your biological father on DNA structures called chromosomes. You received 23 chromosomes from each of your parents. This results in 46 chromosomes, or 2 copies of each of the 23 different chromosomes. Because of this, you end up with 2 copies of each gene. Each of your body cells contain all of this genetic information.

Your 23 pairs of chromosomes are packed with all the information your body needs to perform daily functions. Humans have an estimated 30,000 functional genes, which each contribute to your body’s ability to grow and respond to outside stimuli. On average, each gene codes for about 3 proteins which help direct your body to function properly. Different types of cells express different genes, meaning that certain genes are “turned on”, allowing those cells to perform their specific functions. For example, a cell in your stomach will express different genes than a cell found in your brain, which is why these cells look and function differently. If one or more of the proteins coded by your DNA does not form correctly, your body may be unable to perform essential tasks.

What Else Can Influence Our Genes?

First, let’s discuss mutations. A mutation is a change in the DNA sequence of a gene. Everyone has mutations in their bodies. In fact, you acquire new mutations every single day. In order to create new cells, your current cells must divide. Every time your cells divide, a copy of your DNA must be made for the new cell. This process is called DNA replication. This mechanism happens every day in your body, and sometimes can cause new mutations when mistakes are made during the replication process.

There are different types of mutations that can occur in humans. Some genes may be inherited from your parents; these are called hereditary mutations. Other mutations, called acquired or somatic mutations, may develop during your own lifetime. These may happen as a result of exposure to harmful environments, or mistakes during DNA replication or repair. For example, mutations are known to occur as a result of too much exposure to ultraviolet rays, which can happen when someone spends too much time in the sun without proper protection.

The good news is that not all mutations are bad. Studies have found that the large majority of mutations actually have no impact on your overall health. This means that you could live your whole life with thousands of mutations and never even experience problems as a result. This can happen for a variety of reasons. Often times, mutations may slightly alter the DNA sequence of a certain region, but the mutated sequence may still code for the same protein. Situations like this are possible because the genetic code is redundant, which means that there is more than one DNA sequence that can code for the same protein. This type of mutation is called a silent mutation, and it has no effect on the functioning of your body because all the normal proteins are still made. Your body also has several different systems that check your DNA for any problems and completes repairs when necessary. These systems help prevent your body from expressing any harmful mutations. However, your body may occasionally miss these mutations, and a genetic disorder could result.

Mutations can also be beneficial, although these are much more rare than neutral mutations. A beneficial mutation may allow you to better adapt to your environment or give you a better chance at surviving certain conditions. One example of this could be if a mutation protects you from a certain type of bacteria that could cause disease in the general population. Having this mutation would allow you and your future offspring to have a better chance of survival if this bacterium becomes more common.

The genes you inherited from your parents have a large impact on how your body functions, but these genes are not set in stone. There are certain situations that can change the way a gene is expressed. Epigenetics examines changes in gene expression that occur due to environmental cues, not changes in the DNA sequence. Although these environmental cues do not change the DNA sequences that make up your genes, they can still cause heritable changes in your genome – the complete set of your DNA. This means that any changes in your body, caused by epigenetics, can be passed on to future generations. This occurs because epigenetics can change the expression of DNA within your cells, making some regions active and easy to express, while other areas may be silenced or not expressed at all.

The discovery of epigenetics in the early 1940s revolutionized the field of genetics by showing that your individual lifestyle choices influence what genes are expressed in your body. Your environment affects you sooner than you may think, starting in early development. Research has shown that prenatal conditions, can impact whether a person develops chronic diseases and behavioral disorders later in life. Today, scientists are continuing to discover how the choices you make every day impact your long-term health. Research has shown how factors including nutrition, exercise, and exposure to toxins can change the expression of someone’s genes. Because of this, it is crucial that you make healthy choices that will optimize your genetic health.

What is Genetic Testing?

Commercial genetic testing is a relatively new industry which allows researchers to take a small specimen from someone and determine very specific details about what makes up that person’s genome. These tests commonly require a sample of blood, hair, skin, or spit for testing. After a specimen is collected, it is brought to a lab where the DNA is extracted. Then, different technologies are used to analyze the DNA sample. Doing this allows researchers to see what genes you have, as well as any variations or SNPs that may be unusual.

In recent decades, genetic studies have become much more common. These studies have allowed researchers to gain a better understanding of which genes correlate with different traits, as well as different genetic conditions. The data from these studies can be matched with your genetic files so that researchers are able to identify any mutations that are present. This information can also be used to identify what your risk is for developing certain diseases in the future, such as neurological conditions like Alzheimer’s disease.

At Wild Avocado, we utilize the wealth of information provided from these genetic testing kits in order to provide you with personalized disease risk and performance information. Instead of providing us with a spit or other specimen sample, we are able to utilize the raw data from previous genetic testing you may have used. When you provide us with your genetic file, we are able to analyze your genetics using our detailed algorithms. We will report your results back to you, and you will be able to learn how your genetics are impacting your life today. Your reports will highlight the ways that you can make actionable life changes. By understanding your genetics, you will be able to educate yourself for a lifelong path of healthy living.

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Appendix A Basics Genetics Information, NCBI Staff (NCBI)

Do all gene mutations affect health and development?, NIH Staff (NIH)

Epigenetics: Fundamentals, Staff (What is Epigenetics)

Fasting for Health and Longevity, Nobel Prize Winning Research on Cell Aging, Staff (Blue Zones)

Haplotype, NIH Staff (NIH)

How is direct-to-consumer genetic testing done?, NIH Staff (NIH)

Human Genome Project FAQ, NIH Staff (NIH)

What are proteins and what do they do?, NIH Staff (NIH)

What are single nucleotide polymorphisms (SNPs)?, NIH Staff (NIH)

What is a chromosome?, NIH Staff (NIH)

What is a gene mutation and how do mutations occur?, NIH Staff (NIH)

What is a gene?, NIH Staff (NIH)