Disease in which anamino acid in hemoglobin is abnormal, and at low oxygen concentrations erythrocytes assume sickle shapes or other bizarre forms that block capillaries.

Potentially lethal human disease, inherited as an autosomal recessive, caused by a mutation in a gene coding for the beta subunit of the oxygen-transporting protein haemoglobin. Under conditions of low oxygen tension, the altered beta-globin molecule causes haemoglobin to aggregate forming rod-like arrays that distort the cell membrane forcing red blood cells to become sickle-shaped. The sickled red blood cells are damaged and rapidly removed from the circulation causing anaemia.

a congenital form of anemia occurring mostly in blacks; characterized by abnormal blood cells having a crescent shape