Temporary copies of the information found in DNA; rRNA, or ribosomal RNA, that serve as structural components of protein-making structures known as ribosomes; and finally, tRNA, or transfer RNA, that ferry amino acids to the ribosome to be assembled
This would be called a mutation because it stated above neither of it's parents have it so say for humans both parents have 2 arms which is normal. They have a child and he/she only has one arm thus mutation.