Sickle Cell Anemia: Tests. An inherited disease in which the red blood cells have an abnormal crescent shape, block small blood vessels, and do not last as long as normal red blood cells.Sickle cell anemia is caused by a mutation (change) in a gene.PubMed Health Glossary. (Source: NIH-National Cancer Institute).ickle Cell Anemia: Tests. An inherited disease in which the red blood cells have an abnormal crescent shape, block small blood vessels, and do not last as long as normal red blood cells. Sickle cell anemia is caused by a mutation (change) in a gene. PubMed Health Glossary.