What Are Genetic Mutations?

Genetic mutations might sound like something from a movie, if not something concerning. But in reality, it’s a routine part of your life.

Every day our DNA changes in small ways. But what exactly are these mutations, why do they happen, and how do they affect you?

Here, we'll break down everything you need to know about mutations, from their causes and types to their health implications and why understanding them matters.

What Are Genetic Mutations?

A genetic mutation is a change in your DNA. Some changes are neutral, which don’t affect your health or bodily functions.

But others can be harmful, causing diseases or disorders like cystic fibrosis. However, some changes can result in beneficial traits, such as lactose tolerance in adulthood.

Mutations affect these two types of cells:

• Germline mutations — Passed from parents to children and exist in reproductive cells (eggs and sperm).
• Somatic mutations — Occur  in non-reproductive cells at any time after fertilization and can't be inherited.

Even seemingly big differences among people can start from mutations. For example, different alleles—gene variants born from older mutations—determine eye color and hair texture.

The Main Kinds of DNA Changes

Mutations range from minor changes to substantial rearrangements. These include:

• Frameshift — Changes the reading frame of a gene, usually due to insertions or deletions. A frameshift mutation can ultimately affect the resulting protein's structure and function.

• Duplications — Extra copies of chromosome segments.
• Inversions — DNA segments flipped in reverse orientation.
• Deletion — The loss of a segment of DNA. If a critical gene is deleted, it can lead to the absence or dysfunction of a vital protein.
• Insertion — The addition of extra DNA. If inserted in the wrong place, it can disrupt normal gene function.
• Substitution — These happen when one base pair is replaced with another. Depending on the specific change, it might lead to the production of a faulty protein.
• Nonsense mutations — These mutations create a premature stop codon in the DNA sequence, resulting in the premature termination of protein synthesis.
• Missense mutations — A single nucleotide change leads to substituting one amino acid for another in the encoded protein, potentially affecting its function.
• Chromosomal aberrations — Large-scale mutations, such as deletions, duplications, inversions, or translocations of whole chromosome segments, can cause significant genetic disorders.

What Are Some Harmful Genetic Mutations?

Some mutations can lead to harmful diseases and conditions. Here’s a list of genetic conditions and the mutation that causes them:

• Tay-Sachs Disease (HEXA gene mutation) — A disease that destroys the nervous system, caused by mutations in the HEXA gene. If both parents are carriers, there's a 25% chance their child will have the disease, a 50% chance the child will be a carrier, and a 25% chance the child will be unaffected.
• Cystic Fibrosis (CFTR gene mutation) — Affects the production of mucus, digestive juices, and sweat. Common in Caucasians of Northern European Ancestry but can still occur in other ethnicities.
• Hemophilia (F8 or F9 gene mutation) — A blood clotting disorder, often affecting males. The mutated gene is found in the X chromosome and carrier mothers may pass the gene to their children.
• Sickle Cell Disease (HBB gene mutation) — A blood disorder resulting from gene mutations encoding hemoglobin.
• Thalassemia (HBB and HBA gene mutations) — Limits the natural production of hemoglobin, causing severe anemia.

Understanding common genetic mutations is important for family planning and carrier screening. It provides you with valuable information. Consult with healthcare professionals for guidance and to explore options for managing the risks associated with genetic conditions.

When Do Genetic Mutations Happen?

Genetic mutations happen during major cellular processes such as mitosis and meiosis. Mitosis is responsible for the division of somatic (body) cells, while meiosis is a form of cell division in germ cells, specifically in creating sperm and egg cells.

During mitosis, changes or errors occur in the DNA sequences, resulting in mutations that are passed on to both end-product cells. During meiosis, genetic mutations can occur during genetic recombination.

This occurs when homologous chromosomes exchange genetic material, introducing new gene combinations and enhancing genetic diversity.

Why Do Genetic Mutations Happen?

Genetic mutations can happen because of various factors, such as:

• DNA copying errors — When cells divide and DNA is replicated, there is a chance of errors occurring during this process. Sometimes, incorrect nucleotides may be incorporated, leading to a mutation in the new DNA strand.
• Mutagenic agents — Mutagens can directly damage the DNA structure or interfere with the accurate replication of genetic material.
• Chemical exposure — Chemicals, like those found in tobacco smoke or industrial pollutants, can introduce mutations. These chemicals may react with the DNA molecules, causing modifications in the nucleotide sequence.
• Radiation — Ionizing radiation, such as X-rays or ultraviolet (UV) radiation from the sun, can cause changes in DNA. UV radiation can lead to the formation of thymine dimers, disrupting the normal DNA structure.
• Transposons and mobile genetic elements — Transposons are DNA sequences that can move from one location in the genome to another. Their activity can disrupt genes or promote genetic rearrangements.
• Random mutations — In some cases, genetic mutations are random and occur without any known external cause. 

What Are Some Beneficial Genetic Mutations?

Aside from harmful mutations that can influence our risk of disease, these mutations can be beneficial at times. For instance, your DNA can develop a lactose tolerance, allowing you to digest milk.

There are also Tibetan populations who have developed a unique mutation that allows them to adapt to low-oxygen or high-altitude environments (EPAS1).

Over time, these advantageous mutations spread through populations via natural selection, driving genetic diversity and evolutionary progress.

How Can Genetic Testing Identify Genetic Mutations?

Genetic testing is a powerful tool that can identify genetic mutations. It can provide valuable information about a person’s risk of certain genetic conditions.

DNA tests take a genetic sample (blood, saliva, or tissue), and extract the DNA before analyzing it. The test performs DNA sequencing to analyze the whole genome or target specific regions associated with known genetic conditions.

The DNA is later compared to reference sequences to identify the variations or mutations. Finally, a genetic expert interprets the information to determine any of the following: 

• Pathogenic mutations — Known to cause or increase the risk of a particular condition.
• Variants of Uncertain Significance (VUS) — Genetic mutations with unclear health implications.
• Benign mutations — Changes not associated with disease.

What Do I Do After I Get My Test Results?

After getting your genetic test results, the next step is to seek clinical consultation. Genetic counselors and healthcare professionals can discuss the results with you or your family. 

They explain the implications of identified mutations and potential preventive or therapeutic measures. Identified mutations are assessed for their relevance to health. 

Some mutations may increase the risk of certain diseases, while others may have no significant impact.

Is Genetic Testing Accurate?

Genetic testing is generally accurate, but accuracy depends on many factors. The type, the quality of the laboratory conducting the analysis, and the complexity of interpreting genetic variations affect the test's accuracy.

Advanced techniques like next-generation sequencing have significantly enhanced the accuracy of identifying genetic mutations.

Can I Prevent Genetic Conditions?

Often, there’s very little you can do to prevent genetic conditions. Yet, there are some things you can do to manage and help minimize the risks.

First, consider identifying potential genetic risk through genetic testing. You can work with healthcare professionals to develop health management strategies if you discover a genetic predisposition to certain conditions.

Adopting a healthy lifestyle is another critical aspect of managing genetic risks. Some examples include:

• Maintaining a balanced diet
• Engaging in regular physical activity
• Avoiding tobacco and excessive alcohol consumption
• Managing stress