Diathesis is a medical term meaning “predisposition.” It refers to a natural tendency or susceptibility to disease as a result of genetic or environmental factors. Someone with a diathesis for a condition is at increased risk of developing the condition or experiencing complications as a result of having the condition. Bleeding diathesis, usually caused by genetic blood disorders, is an example; people with blood disorders are more likely to experience problems related to clotting and circulation. Likewise, people in heavily polluted areas can have a predisposition for environmental illnesses.
Genetic conditions can predispose people to a wide range of medical problems and researchers are constantly uncovering new genetic links to disease. For example, metabolic disorders can interfere with the ability to absorb and use nutrients, leading to health problems. People with metabolic disorders can be at risk of malnutrition and other complications because their bodies cannot use nutrients effectively or at all. Likewise, some genetic disorders can create a predisposition for the development of allergies or autoimmune diseases.
A person with a diathesis for given medical conditions may have this noted in a medical chart to make care providers aware. Certain natural tendencies can become concerns during medical procedures or the development of treatment plans. Someone with a bleeding disorder might be a poor candidate for surgery because of increased risks, and if surgery becomes necessary, special steps need to be taken to protect the welfare of the patient. Knowing about this issue ahead of time allows care providers to make plans.
Treatments are sometimes available to address a predisposition or tendency to disease. These can include prophylactics designed to prevent the onset of disease, as well as treatments to manage disease. A person who doesn't produce a particular digestive enzyme could, for example, take an enzyme supplement to replace the missing enzyme, or avoid certain foods that the body cannot digest. Researchers working on gene therapy are interested in ultimately developing treatments to correct the underlying problem so that patients do not require supportive therapies for life.
This term can also be seen used in the diathesis-stress model of behavior. This behavioral model argues that behavioral disorders are the result of a combination of inherited and environmental factors. Someone can have a genetic predisposition to depression or other conditions that interacts poorly with environmental factors known to cause behavioral problems. On their own, genetic and environmental factors may not be enough to lead to the development of a disorder, but when they are combined, they can influence the outcome of a person's behavioral development.