ickle cell disease (SCD) is a group of blood disorders typically inherited from a person’s parents.[2] The most common type is known as sickle cell anaemia.[2] It results in an abnormality in the oxygen-carrying protein haemoglobin found in red blood cells.[2] This leads to a rigid, sickle-like shape under certain circumstances.[2] Problems in sickle cell disease typically begin around 5 to 6 months of age.[1] A number of health problems may develop, such as attacks of pain (known as a sickle cell crisis), anemia, swelling in the hands and feet, bacterial infections and stroke.[1] Long-term pain may develop as people get older.[2] The average life expectancy in the developed world is 40 to 60 years.[2]
Sickle cell disease occurs when a person inherits two abnormal copies of the β-globin gene (HBB) that makes haemoglobin, one from each parent.[3] This gene occurs in chromosome 11.[9] Several subtypes exist, depending on the exact mutation in each haemoglobin gene.[2] An attack can be set off by temperature changes, stress, dehydration, and high altitude.[1] A person with a single abnormal copy does not usually have symptoms and is said to have sickle cell trait.[3] Such people are also referred to as carriers.[5] Diagnosis is by a blood test, and some countries test all babies at birth for the disease.[4] Diagnosis is also possible during pregnancy.[4]
The care of people with sickle cell disease may include infection prevention with vaccination and antibiotics, high fluid intake, folic acid supplementation, and pain medication.[5][6] Other measures may include blood transfusion and the medication hydroxycarbamide (hydroxyurea).[6] A small percentage of people can be cured by a transplant of bone marrow cells.[2]
As of 2015, about 4.4 million people have sickle cell disease, while an additional 43 million have sickle cell trait.[7][10] About 80% of sickle cell disease cases are believed to occur in Sub-Saharan Africa.[11] It also occurs relatively frequently in parts of India, the Arabian Peninsula, and among people of African origin living in other parts of the world.[12] In 2015, it resulted in about 114,800 deaths.[8] The condition was first described in the medical literature by American physician James B. Herrick in 1910.[13][14] In 1949, its genetic transmission was determined by E. A. Beet and J. V. Neel.[14] In 1954, the protective effect against malaria of sickle cell trait was described.[14]