Deleting the same region from the female parent gives Angelmann syndrome. Thus, these regions are imprinted differently in the two parents. Causes slightly subnormal performance in offspring of first cousin marriages. A tumor or neoplasm is a mass of cancerous cells. Some specific inherited cancers known.
Mutagens are carcinogens.
Sometimes liver extracts are necessary to convert chemicals into carcinogens. Both DNA and RNA viruses can do this. RNA viruses of retrovirus type are most important. Sarcoma virus causes tumors in chickens. Avian leukosis virus very similar, but no tumors.