1910: James Herrick, a doctor in Chicago in the USA notices ?peculiar elongated and sickle shaped? blood cells in Walter Clement Noel, a dental student from Grenada suffering from anaemia. Sickle cell disease, though known for years in Africa, was then formally reported in the US medical journal, Archives of Internal Medicine.

1917: The genetic basis for sickle cell is first suggested by Victor Emmel, an American anatomist, in the US medical journal, Archives of Internal Medicine.

1922: Three more cases are reported in the USA and the disease is formally named.

1923: Doctors at the Maryland-based Johns Hopkins University conclude sickle cell disease is an ?autosomal recessive characteristic? - two copies of the gene must be present for it to be expressed.

1927: It is discovered that ?sickling? happens because of a lack of oxygen.

1940: The connection is made between abnormal haemoglobin and the tendency of red blood cells to sickle.

1949: It is determined that carrying the sickle cell trait can be symptomless.

1954: Anthony Allison hypothesizes that the sickle cell trait offered protection against malaria. As more research was done, it is discovered that those with the sickle cell trait, not the disease, are protected against malaria. But those with sickle cell disease either die from the blood disorder or die after coming into contact with malaria because of a weakened immune system. Subsequent research has called into question the sickle cell trait?s ability to protect against malaria.

1970s: Forced testing for black people proliferates when sickle cell screening programmes began in the USA.

1979: Calculations suggest the sickle cell gene developed 70,000-150,000 years ago.

1994: It is recognized that all of the areas where sickle cell disease originated have been, or are now, endemic locations of malarial infestation.

1995: Hydroxyurea, an anti-cancer drug, is found to be an effective therapy in reducing complications from SCD. 

1996: Bone marrow transplants are now used to treat sickle cell disease in children. 

1996: The Federation of Associations Combating Sickle Cell Disorder in Africa (FALDA) is formed.

2000: The introduction of pneumococcal vaccine greatly reduces child mortality in the USA as those with SCD were at high risk of developing pneumococcal meningitis.

2003: Hydroxyurea increases life expectancy for sickle cell patients. 

Sickle Cell Disease is a group of inherited red blood cell disorders. Normal red blood cells are round like doughnuts, and they move through small blood tubes in the body to deliver oxygen. Sickle red blood cells become hard, sticky and sickle shape. When these hard and pointed red cells go through the small blood tube, they clog blood flow and break apart. This can cause pain, tissue damage and a low blood count, or anemia.

SCD affects millions of people throughout the world and is  particularly common among those whose ancestors come from subSaharan Africa; regions in the Western Hemisphere (South America, the Caribbean, and Central America); Saudi Arabia; India; and Mediterranean countries such as Turkey, Greece, and Italy.

In Canada Sickle Cell Anemia affects 5000 people. 1 out of every 2500 births will have Sickle Cell anemia .



Frequently asked questions

What makes red blood cells sickle?
There is a substance in the red blood cell called hemoglobin that. One little change in this substance causes the hemoglobin to form long rods in the red blood cell when it gives away oxygen. These rigid rods change the red bloods cells into a sickle shape.
How do you get sickle cell anemia?
You inherit the disorder from you parents. You are born with the sickle cell hemoglobin and it is present for life.  

How can I be tested?
A simple blood test called the hemoglobin electrophoresis can be done by your doctor or local sickle cell foundation. This test will tell if you are a carrier of the sickle cell trait or if you have the disease.  New born babies can also be screened for sickle cell disease.
What is sickle cell trait?
A person with sickle cell trait carries one sickle hemoglobin producing gene and one normal hemoglobin gene. Normal hemoglobin is called type A. Sickle hemoglobin called S. Sickle cell trait is the presence of hemoglobin AS on the hemoglobin electrophoresis. This will NOT cause sickle cell disease. Other hemoglobin traits are AC and AE traits.
What are the other forms of sickle cell disease?
There are three common types of sickle cell disease.

  • Hemoglobin SS or  sickle cell anemia
  • Hemoglobin SC disease
  • Hemoglobin sickle beta-thalassemia

Each of these can cause sickle pain episodes and complications, but some are more common than others. An increase in fetal hemoglobin can protect the red blood cells from sickling in all of these forms of sickle cell disease.  The medication hydroxyurea increases fetal hemoglobin.

Causes and risks
Sickle cell anemia results from a condition in which a person's red blood cells carry almost exclusively an abnormal type of hemoglobin, called Hemoglobin S. For this to occur, the person must have received a Hemoglobin S gene from each parent.
If a person has received a Hemoglobin S gene from only one parent, and a normal hemoglobin gene from the other, that person is said to have sickle trait. Persons with sickle trait rarely have problems and, unless tested, may be unaware that they carry the gene. A few people with sickle trait have problems at high altitudes, where there is less oxygen.  The chances of inheriting sickle cell anemia from parents with the sickle cell trait is illustrated below.

Someone who inherits hemoglobin S from one parent and another type of abnormal hemoglobin from the other parent will have another form of sickle cell disease such as sickle cell-b 0 thalassemia, hemoglobin SC disease, or sickle cell-b + thalassemia. Persons with these forms of sickle cell anemia rarely have problems and, unless tested, may be unaware that they carry the gene.  The inheritance of sickle trait is illustrated on the panel.

Sickle cell anemia may become life threatening when damaged red blood cell break down (hemolytic crisis) or bone marrow fails to produce blood cells (aplastic crises). Repeated crises can cause damage to the kidneys, lungs, bone, liver (incidence less than two percent), and Blocked blood vessels and damaged organs can cause painful episodes.
These painful crises, which occur in 70% of patients, can last hours to days, affecting the bones of the back, the long bones and the chest. Some patients have one episode every few years, while others have many episodes per year. The crises can be severe enough to require admission to the hospital for pain control and intravenous fluids.
Many manifestations of this disease are a result of the fragility and inflexibility of the sickle red blood cells. When patients experience, infection, and low oxygen supply, these fragile red blood cells assume a crescent shape, causing red blood cell destruction and thickening of the blood.


Sickle cell anemia can only result when two carriers with sickle cell trait have a child together. Therefore, genetic counseling is recommended for all carriers of sickle cell trait. Prenatal diagnosis of sickle cell anemia is also available. Prompt treatment of infections, adequate oxygenation, and preventing dehydration may prevent sickling of red blood cells. Antibiotics and vaccinations may prevent infections. General health visits with a physician are recommended to ensure the patients are getting adequate nutrition, maintaining proper activity levels, and receiving proper vaccinations.
In incentive spirometry, the patient breathes into a plastic tube that has a ball inside. By trying to breathe hard enough to force the ball up the tube, the patient receives more oxygen. Using this treatment when chest pains begin may decrease the complications of acute chest syndrome. Prenatal diagnosis is now possible for couples at risk of producing a child with sickle cell anemia.


Researchers have found that several chemical compounds, including urea, carbamyl phosphate, and sodium cyanate, can reverse the sickling process. However, these drugs can have serious side effects and, under some testing procedures, have not proved as effective as researchers originally hoped. Researchers are experimenting with these and other drugs in an effort to find a safe, effective treatment. Currently, blood transfusions are usually given only when the anemia is severe enough to cause serious illness.


Canada Sickle Cell Statistics.