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What does it mean to have a genetic predisposition to a disease?
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Mutationsanddisorders

What does it mean to have a genetic predisposition to a disease?

A genetic predisposition is an increased likelihood of developing a disease based on inherited genetic variations that contribute to, but do not directly cause, the condition.

Understanding Genetic Susceptibility

A genetic predisposition (or genetic susceptibility) results from specific genetic variations often inherited from a parent. These changes contribute to the development of a disease but do not guarantee it. Some individuals with a predisposing variation will never develop the disease, while others will, even within the same family.

Impact of Genetic Variations

Genetic variations can have varying effects on disease risk:

  • Large effects: Certain variants in the BRCA1 or BRCA2 genes greatly increase the risk of breast and ovarian cancer.
  • Small effects: Variations in genes such as BARD1 and BRIP1 appear to have a much smaller impact on breast cancer risk.

Polygenic Risk and Multifactorial Disorders

Current research focuses on identifying common genetic changes that each have a small effect on disease risk. When combined, changes in many different genes may significantly increase the risk for common conditions, including cancer, obesity, diabetes, heart disease, and mental illness. Researchers use a polygenic risk score to estimate an individual’s risk based on these combinations.

Diseases caused by a combination of genetic factors (including modifiers), lifestyle, and environmental factors are described as multifactorial. While a person's genetic makeup cannot be altered, lifestyle and environmental modifications—such as frequent screenings or maintaining a healthy weight—may help reduce risk in those with a genetic predisposition.

Frequently Asked Questions

In the United States, the Genetic Information Nondiscrimination Act (GINA) prevents health insurance providers and employers from requesting genetic test results or using them to deny coverage or determine premiums. However, GINA does not apply to life insurance, disability insurance, or long-term care insurance policies, where insurers may legally evaluate genetic risk depending on individual state regulations.
No. A genetic predisposition indicates an elevated risk, not a certainty. This concept, known as incomplete penetrance, means that additional elements—such as environmental exposures, lifestyle habits, and other modifier genes—determine whether the disease actually manifests. Many individuals carrying predisposing variations live full lives without ever developing the condition.
Single-gene testing looks for rare, high-impact variants in specific individual genes (such as BRCA1 or MLH1) that carry a substantial lifetime risk on their own. In contrast, a polygenic risk score (PRS) analyzes hundreds to thousands of common, small-effect genetic variants across your entire genome, calculating an aggregate statistical score to estimate your relative risk for complex conditions like coronary artery disease or type 2 diabetes.
First, consult a board-certified genetic counselor or specialist to interpret your absolute risk rather than relative risk alone. Actionable steps generally include establishing tailored clinical surveillance—such as initiating mammograms or colonoscopies at an earlier age—considering risk-reducing medications or prophylactic surgeries when appropriate, and optimizing lifestyle habits such as diet, exercise, and avoidance of tobacco.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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