Variant

A genetic variant is a difference in a person’s DNA sequence, when compared to a standard, or “reference” sequence.  All people have many such variants.  Some are important for differences between individuals and groups, while others are random changes that have no significance at all.  Some diseases result from a single DNA change in a particular gene.  It is important to say that, overall, most changes do not cause disease.  In addition, some gene variants can influence a person’s risk of developing a disease, without making it obligatory for them to ever develop any symptoms.