Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Sickle-cell disease, or sickle-cell anaemia (or drepanocytosis), is a genetic life-long blood disorder characterized by red blood cells that assume an abnormal, rigid, sickle shape. Sickling decreases the cells'' flexibility and results in a risk of various complications. The sickling occurs because of a mutation in the hemoglobin gene. Life expectancy is shortened, with studies reporting an average life expectancy of 42 and 48 years for males and females, respectively.