0 or 1 of previous expression; also forces minimal matching when an expression might match several strings within a search string. \. Preceding one of the above, it makes it a literal instead of a special character. Preceding a special matching character, see below.
sickle cell disease. Sickle cell anemia, a common form of sickle cell disease, is caused by a particular mutation in the HBB gene. This mutation results in the production of an abnormal version of beta-globin called hemoglobin S or HbS. In this condition, hemoglobin S replaces both beta-globin subunits in hemoglobin.
Sickle Cell. These are the sickle-shaped blood cells of someone with sickle cell anemia, a genetic disease common among those of African descent. Sickle cell anemia is the result of a point mutation, a change in just one nucleotide in the gene for hemoglobin.This mutation causes the hemoglobin in red blood cells to distort to a sickle shape when deoxygenated. The sickle-shaped blood cells clog in the capillaries, cutting off circulation.ickle Cell. These are the sickle-shaped blood cells of someone with sickle cell anemia, a genetic disease common among those of African descent. Sickle cell anemia is the result of a point mutation, a change in just one nucleotide in the gene for hemoglobin.