Genetic disorders are caused by changes or mutations in a person's DNA, which can range from tiny to severe. These changes can be inherited from a parent or acquired during a person's lifetime. There are three main types of genetic disorders: chromosomal disorders, complex disorders, and single-gene disorders. Chromosomal disorders occur when there is an abnormality in the number or structure of chromosomes.
An example of this type of disorder is sickle cell anemia, in which chromosomes (or parts of chromosomes) are missing or changed. People with this condition have red blood cells that are shaped like a sickle, which can cause anemia and other health problems. Complex disorders involve mutations in two or more genes, such as albinism, which is a group of genetic conditions that cause people to have no color or very little color in their hair, skin, and eyes. Apert syndrome is another example of a complex disorder, which causes an abnormal skull shape and fusion of the fingers and toes. Single-gene disorders, also known as Mendelian or monogenetic inheritance, are caused by changes or mutations in the DNA sequence of a single gene.
Thousands of single-gene disorders are known and can often be traced back to families. Examples of single-gene disorders include Fabry disease, which is a rare disorder that can affect many parts of the body and cause many different types of symptoms, and Down syndrome (or trisomy 21), which is a common genetic disorder that occurs when a person has three copies of chromosome 21. Multifactorial inheritance is also associated with hereditary traits such as fingerprint patterns, height, eye color, and skin color. If you have a family history of a genetic disorder, you may want to consider genetic counseling to see if genetic testing is right for you. Although a person's genetic makeup cannot be altered, certain lifestyle and environmental changes (such as getting tested for more common diseases and maintaining a healthy weight) can reduce the risk of disease in people with a genetic predisposition. If there is a family history, DNA testing for genetic disorders can be an important part of starting a family. To understand the causes of genetic disorders, it's helpful to learn more about how genes and DNA work.
Genes are made up of DNA molecules that contain instructions for how our bodies develop and function. When these instructions are disrupted by mutations or changes in the DNA sequence, it can lead to genetic disorders. If you or a loved one has a genetic disorder, it's important to seek care from an experienced specialist. Genetic counselors can provide information about the risks associated with certain conditions and help families make informed decisions about their health care.