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A type of variant that contributes towards a disease phenotype (clinical signs and symptoms), but is not causative on its own.

Use in clinical context

Most phenotypes are not caused by a single genetic variant but several genetic variants, often combined with environmental effects. For example, in the case of type 2 diabetes, there are many known risk factors for developing the disease, with obesity being a large contributing factor, but not everyone who is overweight will develop diabetes. It is likely that, along with such environmental risk factors, there are disease-modifying variants that predispose, or protect individuals from diseases.

Other disease-modifying variants alter the presentation of a disease/condition. This may alter the severity of presentation (even including not developing the condition at all) or include/remove particular symptoms. This may make it more difficult to diagnose some diseases and conditions, or to establish inheritance patterns.

Last updated on 22nd October, 2020