copy of a gene that usually lacks introns and other essential DNA sequences
necessary for function. Pseudogenes, though genetically similar to the original
functional gene, are not expressed and often contain numerous mutations.
Definition from: GeneReviews
from the University of Washington and the National Center for Biotechnology Information
A pseudogene is a DNA sequence that resembles a gene but has been mutated into an inactive form over the course of evolution. A pseudogene shares an evolutionary history with a functional gene and can provide insight into their shared ancestry.