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Genetic Disorders

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Summary

What are genetic disorders?

Genetic disorders are health conditions caused by changes (also called mutations or variants) in your genes. Genes are parts of DNA found in your cells that carry instructions for how your body grows, develops, and functions. Many genes tell your body how to make proteins, which are needed for your body to work properly.

What causes genetic disorders?

A genetic disorder happens when a gene variant changes how a protein is made. The variant may cause the protein to work poorly or not be made at all. If genes don't make the right proteins, or don't make them correctly, it can lead to a genetic disorder.

Not all gene changes cause disease. Often, these changes have no effect. But sometimes, even a small change in DNA can affect how proteins are made.

Gene variants can be grouped into two main types:

Inherited variants (also called germline variants) are passed down from your parents. They come from egg or sperm cells.
Non-inherited (also called somatic variants) are not passed down from your parents. They happen during your lifetime. They may be caused by things like harmful chemicals or ultraviolet (UV) rays from the sun.

What are the types of genetic disorders?

Genetic disorders may be caused by:

Single gene disorders are caused by changes in one gene. Examples can include sickle cell anemia, where a change in a single gene can cause the condition, and Charcot-Marie-Tooth disease, where a variant in one of many different genes can cause the condition.
Chromosomal disorders are caused by missing, extra, or altered chromosomes. Chromosomes are structures that carry genes. These disorders involve changes in the number of chromosomes people have or changes in the structure of one or more chromosomes. An example is Down syndrome, which is caused by an extra copy of chromosome 21.
Complex (multifactorial) disorders are caused by changes in many genes. Each change alone may not cause the disease, but together they increase the risk. Lifestyle and environmental factors, such as exercise, diet, or exposure to pollutants, also play a role. Colon cancer is an example.

What are the different ways a genetic disorder can be inherited?

Some genetic conditions are passed down through families (inherited) in one of several patterns, depending on the specific gene involved.

Patterns of inheritance can include:

Dominant means you only need one changed gene to cause the condition.
Recessive means you need two changed copies of the gene (one from each parent) for the condition to occur.
X-linked conditions involve genes located on the X chromosome. These conditions often affect males more frequently.
Mitochondrial conditions are passed down by the mother.

How are genetic disorders diagnosed?

Your health care provider may check for a genetic condition based on:

A physical examination.
Your personal medical history.
Your family health history.
Laboratory tests, including genetic testing.

NIH: National Library of Medicine

Start Here

Genetic and Chromosomal Conditions (March of Dimes Foundation) Also in Spanish
Genetic and Rare Diseases Information Center
Genetic Disorders (National Human Genome Research Institute)
Genetics: MedlinePlus Genetics (National Library of Medicine) Also in Spanish
How can gene variants affect health and development?: MedlinePlus Genetics (National Library of Medicine) Also in Spanish

Diagnosis and Tests

Genetic Testing: MedlinePlus Health Topic (National Library of Medicine) Also in Spanish
How are genetic conditions diagnosed?: MedlinePlus Genetics (National Library of Medicine) Also in Spanish
Newborn Screening: MedlinePlus Health Topic (National Library of Medicine) Also in Spanish
Progeria Research Foundation Diagnostic Testing Program (Progeria Research Foundation, Inc.)

Treatments and Therapies

How are genetic conditions treated or managed?: MedlinePlus Genetics (National Library of Medicine) Also in Spanish

Related Issues

What Is Genetics? (National Institute of General Medical Sciences)

Specifics

About Poland Anomaly (National Human Genome Research Institute)
About Progeria (National Human Genome Research Institute)
Cryopyrin-Associated Autoinflammatory Syndromes (CAPS) (American College of Rheumatology) Also in Spanish
Frequently Asked Questions about Genetic Disorders (National Human Genome Research Institute)
Genetics: MedlinePlus Genetics (National Library of Medicine) Also in Spanish
Help for People with Undiagnosed Medical Conditions (National Organization for Rare Disorders)
Infantile Neuroaxonal Dystrophy (National Institute of Neurological Disorders and Stroke)
Noonan Syndrome (Mayo Foundation for Medical Education and Research)
Triple X Syndrome: Symptoms and Causes (Mayo Foundation for Medical Education and Research) Also in Spanish
VEXAS Syndrome (National Institute of Arthritis and Musculoskeletal and Skin Diseases)
What are complex or multifactorial disorders?: MedlinePlus Genetics (National Library of Medicine) Also in Spanish
What are the different ways a genetic condition can be inherited?: MedlinePlus Genetics (National Library of Medicine) Also in Spanish
What does it mean if a disorder seems to run in my family?: MedlinePlus Genetics (National Library of Medicine) Also in Spanish
Williams Syndrome (Genetic and Rare Diseases Information Center) Also in Spanish

Statistics and Research

Human Genome Project (National Human Genome Research Institute)

Clinical Trials

ClinicalTrials.gov: Genetic Diseases, Inborn (National Institutes of Health)
ClinicalTrials.gov: Progeria (National Institutes of Health)

Journal Articles References and abstracts from MEDLINE/PubMed (National Library of Medicine)

Reference Desk

Chromosome Abnormalities (National Human Genome Research Institute) Also in Spanish
Genetic Testing Registry (National Center for Biotechnology Information)
How are genetic conditions and genes named?: MedlinePlus Genetics (National Library of Medicine) Also in Spanish
Talking Glossary of Genomic and Genetic Terms (National Human Genome Research Institute) Also in Spanish

Find an Expert

Children

Campomelic Dysplasia (For Parents) (Nemours Foundation) Also in Spanish
Cartilage Hair Hypoplasia (For Parents) (Nemours Foundation) Also in Spanish
CLOVES Syndrome (For Parents) (Nemours Foundation) Also in Spanish
Ellis-Van Creveld Dysplasia (For Parents) (Nemours Foundation) Also in Spanish
Gene Changes (Mutations) (Nemours Foundation) Also in Spanish
Genes and Genetics (For Parents) (Nemours Foundation) Also in Spanish
Genetics (For Parents) (Nemours Foundation) Also in Spanish
Multiple Epiphyseal Dysplasia (For Parents) (Nemours Foundation) Also in Spanish
RareDx for Parents: A Guide to Navigating a Rare Disease Diagnosis (National Organization for Rare Disorders) Also in Spanish
What Is a Gene? (Nemours Foundation) Also in Spanish
What Is a Pediatric Geneticist? (American Academy of Pediatrics) Also in Spanish

Women

Genetic Disorders and Pregnancy (American College of Obstetricians and Gynecologists)

Patient Handouts

Genetics (Medical Encyclopedia) Also in Spanish

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