Heartworms are spread to dogs through mosquito bites. Up to 14 inches long, a heartworm lives in the heart and the arteries that carry blood from the heart to the lungs. Heartworms affect how the heart functions and how blood clots and is likely to cause death if untreated. Monthly heartworm preventives are effective.
missense mutation. A substitution of a single DNA nucleotide for another. This results in the transcription of a different amino acid than is normally found in the protein coded by the gene. Missense mutations are found in diseases such as sickle cell anemia.
1 A nonsense mutation is the same as a missense mutation except the resulting codon codes for a STOP signal. 2  The result is a premature termination of translation. 3  The protein is shorter than usual and does not contain all the amino acids that it should.