What Is a Gene Mutation? A gene mutation (myoo-TAY-shun) is a change in one or more genes. Some mutations can lead to genetic disorders or illnesses. What Are Genes? Genes are short sections of DNA. They determine our traits, which are things like hair color, height, body type, and other things that make a person unique. Genes also play a role in a person's risk for some diseases and health conditions. Each of us has about 24,000 different types of genes. What Is DNA? DNA (deoxyribonucleic acid) is the carrier of all our genes. Each person gets one copy of DNA from their mother and one copy from their father. DNA creates a code using four chemicals called nucleotides (NEW-klee-uh-tydes). This code determines which genes a person has. DNA is located inside the chromosomes. What Is a Chromosome? A chromosome (KRO-muh-sohm) is an X-shaped thread-like structure in the body's cells. It contains DNA. Humans have 23 pairs of chromosomes. What Causes a Gene Mutation? A gene can mutate because of: a change in one or more nucleotides of DNA a change in many genes loss of one or more genes rearrangement of genes or whole chromosomes Do Parents Pass Gene Mutations to Children? If a parent carries a gene mutation in their egg or sperm, it can pass to their child. These hereditary (or inherited) mutations are in almost every cell of the person's body throughout their life. Hereditary mutations include cystic fibrosis, hemophilia, and sickle cell disease. Other mutations can happen on their own during a person's life. These are called sporadic, spontaneous, or new mutations. They affect only some cells. Damage from the sun's ultraviolet radiation or exposure to some types of chemicals can lead to new mutations. These mutations are not passed from parents to their children. Do All Gene Mutations Cause Health Problems? Most gene mutations have no effect on health. And the body can repair many mutations. Some mutations are even helpful. For example, people can have a mutation that protects them from heart disease or gives them harder bones. Back to Articles Related Articles All About Genetics Read the basics about genetics, including how certain illnesses, or increased risks for certain illnesses, pass from generation to generation. Read More Gene Therapy and Children Gene therapy carries the promise of cures for many diseases and for types of medical treatment most of us would not have thought possible. Read More Genetic Testing Advances in genetic testing help doctors diagnose and treat certain illnesses. The type of test done depends on which condition a doctor checks for. Read More Prenatal Genetic Counseling Genetic counselors work with people who are either planning to have a baby or are pregnant to determine whether they carry the genes for certain inherited disorders. Find out more. Read More What Is Epigenetics? Epigenetics - the idea that environmental factors can change the health not only of the people who are exposed to them, but also the health of their descendants - is something we'll be hearing more about. Read More Sickle Cell Disease Sickle cell disease is a blood disorder that makes red blood cells change shape and cause health problems. Find out how to help your child. Read More Sickle Cell Trait Children who inherit one sickle cell gene have sickle cell trait. They usually don't get symptoms of sickle cell disease. Read More The Basics on Genes and Genetic Disorders Genes play an important role in how we look and act, and even in whether we get sick. This article gives the lowdown on genes, genetic disorders, and new research into gene therapy. Read More What Is a Gene? Why does one kid have green eyes while another kid's eyes are brown? It's all in the genes! Find out how genes work, what happens when there are problems with genes, and more. Read More Word! Genetics Genetics is the study of the way physical traits and characteristics get passed down from one generation to the next. Read More Word! Heredity If people say you look like your parents, they're probably talking about heredity. Read More Word! Chromosomes Your body is made up of billions of cells, which are too small to see without a strong microscope. Read More Sickle Cell Disease Sickle cell disease is a blood disorder that makes red blood cells change shape and cause health problems. Find out more in this article for teens. Read More Will I Pass Sickle Cell Disease on to My Children? Find out what the experts say. Read More Note: All information is for educational purposes only. For specific medical advice, diagnoses, and treatment, consult your doctor. © 1995-2021 KidsHealth®. All rights reserved. Images provided by The Nemours Foundation, iStock, Getty Images, Veer, Shutterstock, and Clipart.com.