Definition
When a number of genes are associated with a single condition, and variants in any of these could result in someone being affected.
Use in clinical context
Some conditions are always caused by variants in one gene, but conditions with genetic heterogeneity can be caused by variants in multiple genes. For example, familial hypercholesterolaemia can result from variants in one of four different genes.
Individuals with conditions that have genetic heterogeneity usually only have a variant in one gene, but it is possible to have variants in more than one gene associated with the condition. This can have implications for the presentation of the condition and for screening family members, to ensure that all familial variants are tested for.
