allelic heterogeneity
(uh-LEE-lik HEH-teh-roh-jeh-NEE-ih-tee)
A term that describes when different mutations (changes) in a single gene cause the same disease or condition. Each mutation by itself is enough to cause the disease or condition. For example, cystic fibrosis (an inherited disorder that affects the lungs and digestive system) is caused by having one of many different mutations in the CFTR gene.