mutant gene vs CFTR

mutant gene and CFTR both are nouns.

Word	Noun	Adjective	Verb	Adverb
mutant gene	Yes	No	No	No
CFTR	Yes	No	No	No

As nouns, CFTR is a hyponym of mutant gene; that is, CFTR is a word with a more specific, narrower meaning than mutant gene:

mutant gene: a gene that has changed so that the normal transmission and expression of a trait is affected
CFTR: the gene that is mutated in cystic fibrosis

Other hyponyms of mutant gene include cystic fibrosis transport regulator.

mutant gene (noun)	CFTR (noun)
a gene that has changed so that the normal transmission and expression of a trait is affected	the gene that is mutated in cystic fibrosis