What is Sickle-Cell Anaemia?

What is Sickle-Cell Anaemia?

The disorder affects the red blood cells which contain a special protein called haemoglobin (Hb for short). The function of haemoglobin is to carry oxygen from the lungs to all parts of the body.

People with SICKLE CELL ANAEMIA have Sickle haemoglobin (HbS) which is different from the normal haemoglobin (HbA). When sickle haemoglobin gives up its oxygen to the tissues, it sticks together to form long rods inside the red blood cells making these cells rigid and sickle-shaped. Normal red blood cells can bend and flex easily.

Blocked blood vessels:

Because of their shape, sickled red blood cells can’t squeeze through small blood vessels as easily as the almost donut-shaped normal cells. This can lead to these small blood vessels getting blocked which then stops the oxygen from getting through to where it is needed. This in turn can lead to severe pain and damage to organs.

Everyone has two copies of the gene for haemoglobin; one from their mother and one from their father. If one of these genes carries the instructions to make sickle haemoglobin (HbS) and the other carries the instructions to make normal haemoglobin (HbA) then the person has Sickle Cell Trait and is a carrier of the sickle haemoglobin gene. This means that this person has enough normal haemoglobin in their red blood cells to keep the cells flexible and they don’t have the symptoms of the sickle cell disorders. They do however have to be careful when doing things where there is less oxygen than normal such as scuba diving, activities at high altitude and under general anaesthetics.

If both copies of the haemoglobin gene carry instructions to make sickle haemoglobin then this will be the only type of haemoglobin they can make and sickled cells can occur. These people have Sickle Cell Anaemia and can suffer from anaemia and severe pain. These intense and severe attacks are known as Crises. Over time Sickle Cell sufferers can experience damage to organs such as liver, kidney, lungs, heart and spleen. Death can be an outocme of the disorder.

Another problem is that red blood cells containing sickle haemoglobin do not live as long as the normal 120 days and this results in a chronic state of anaemia. In spite of this, a person with sickle cell disorder can attend school, college and work. People with sickle cell disorder need regular medical attention particularly before and after operations, dental extraction and during pregnancy. Many hospitals arrange follow-up appointments and it is advisable to discuss with the doctors questions concerning schooling, strenuous exercise, family planning, suitable types of employment and air travel. When a person is found to have a sickle cell disorder it is important that all members of the family be tested. They will not necessarily have sickle cell disorder but may be healthy carriers of a sickle cell trait.

Other types of Sickle Cell Disorders (SCDs):

There are also other different types of haemoglobin such as HbC and beta thalassaemia, that can combine with sickle haemoglobin to cause sickling disorders. When someone carries the gene for beta-thalassaemia they cannot make as much HbA as they should. If this is combined with the HbS gene then more of their total amount of haemoglobin is HbS and they can suffer from what is usually a milder form of sickle cell disorder than sickle cell anaemia.

Who Gets SCDs?

The different kinds of SCD and the different traits are found mainly in people whose families come from Africa, the Caribbean, the Eastern Mediterranean, Middle East and Asia.* In Britain SCD is most common in people of African and Caribbean descent. It is estimated there are more than 15,000 adults and children with SCD in Britain at present. Every year about 350 babies are born with SCD. There are other inherited conditions that mainly affect other groups, e.g. Cystic Fibrosis in Europeans, and Tay-Sachs disease in Jewish people.

What Sickle Cell Disorders are Not

People are often confused and disturbed by some of the incorrect information they have received about SCD. Sickle Cell Disorders

 - are not leukaemia / are not cancer / are not white blood cells eating up red blood cells
 - are not infectious – you cannot `catch it’ as you would catch measles or a cold

Sickle Cell Disorder is a condition which is inherited from both parents. This means that people are born with it, just as they are born with other characteristics such as eye colour, hair texture and height.

Information from: Sickle Cell Society UK http://www.sicklecellsociety.org/resources/what-is-sickle-cell-anaemia/

Sickle Cell Trait

Sickle cell trait is an inherited blood disorder that affects 1 million to 3 million Americans and 8 to 10 percent of African Americans. Sickle cell trait can also affect Hispanics, South Asians, Caucasians from southern Europe, and people from Middle Eastern countries. More than 100 million people worldwide have sickle cell trait.

Unlike sickle cell disease, a serious illness in which patients have two genes that cause the production of abnormal hemoglobin (the substance in red blood cells that helps carry oxygen), individuals with sickle cell trait carry only one defective gene and typically live normal lives. Rarely, extreme conditions such as severe dehydration and high-intensity physical activity can lead to serious health issues, including sudden death, for individuals with sickle cell trait.

 - If an individual has sickle cell trait, it means that he/she has inherited (carries) a single copy of the gene that causes sickle cell disease. It is NOT a disease.

 - Sickle cell trait can never become sickle cell disease.

In general, people with sickle cell trait enjoy normal life spans with few medical problems related to sickle cell trait. It is possible, however, for individuals with sickle cell trait to pass the gene to their children.

Information from the American Society of Hematology - ​http://www.hematology.org/Patients/Anemia/Sickle-Cell-Trait.aspx

The Thalassaemia Society of NSW recommends testing. A special blood test (haemoglobin electrophoresis) can tell you whether you have a sickle cell disorder or are a healthy carrier, e.g. for sickle cell trait. Routine screening should take place for all pregnant women, all newborn babies, and before anaesthesia, either at hospital or dental clinics.

When both parents carry a genetic trait for a haemoglobin disorder, there is a 25% risk that their child will inherit the full disorder, which requires life-long treatment.


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