I want to know the answer to the following question:
What are functional copies of a gene which have a loss of function due to mutation called?
All the background I'm provided with is that "Sometimes, gene duplication may result in a nonfunctional copy of a gene, or a functional copy may be subject to mutations that result in loss of function; such nonfunctional genes are called pseudogenes.:7.6". Is that enough to answer the question?