Most of our physical characteristics are inherited through the genes we take from our parents; for example, the shape of our nose, the colour of our skin and eyes. We also inherit our haemoglobin (Hb) type from our parents, through the genes.

Haemoglobin (Hb) is the substance in the blood which gives it its red colour. It carries oxygen (air)around the body and, therefore, it is vital for maintaining life. Without red blood cells, the body cannot function.

World wide the usual and most common adult haemoglobin type is known by the letter A. Where a person has inherited haemoglobin A from both parents they will have the usual haemoglobin combination AA (Hb AA). In this instance, the red blood cells are round, able to carry oxygen (air) well, and they flow easily aound the body. (see Diagram 1)
	Diagram 1

A small proportion of people inherit unusual haemoglobins; for example, sickle haemoglobin (S), haemoglobin C (C), or any other unusual haemoglobins. There are approximately 400 unusual haemoglobins known in humans.

Some people inherit one usual adult haemoglobin from one parent and one sickle haemoglobin from the other and are said to have sickle cell trait (Hb AS). These individuals have healthy red blood cells, they are not ill, they are well and do not have any symptoms. It cannot change into any other form of haemoglobin later in life.

Sickle cell is found in areas of the world where malaria is, or was, common. It has been shown that sickle cell trait protects very young children from the harmful effects of a serious type of malaria; therefore, sickle cell trait is very useful in those parts of the world.

Sickle cell trait is found in people whose ancestors originate from Asia, Africa, the Mediterranean islands, the Middle and Far East, and South America. Because of migration, it is also found in Caribbeans, Black British, Black Americans, and others whose ancestors originally came from parts of the world where sickle haemoglobin is common.

For example, it is estimated that approximately:

1 in every 10 Afro-Caribbeans

1 in every 4 West Africans

1 in every 50 Asians

1 in every 100 Northern Greeks

have sickle cell trait. They are perfectly healthy and do not have a disease or illness.

In fact many athletic people have sickle cell trait and it does not affect their physical performance in any way. The red blood cells of people with sickle cell trait (Hb AS) remain round and carry oxygen (air) normally. Because there are no symptoms associated with sickle cell trait, these individuals will not know that they carry this unusual haemoglobin unless they have a special blood test, or they have a child with someone who also has an unusual haemoglobin and their child is born with a sickle cell syndrome.

For a couple who BOTH have sickle cell trait (Hb AS), EACH time they expect a child there is a 1 in 4 chance that their child could inherit sickle cell anaemia (Hb SS), which is one of the sickle cell syndromes.


WHAT ARE SICKLE CELL SYNDROMES?

Sickle cell syndromes, sometimes abbreviated as (SCS), are commonly called sickle cell "diseases". For the purposes of this website, the term "syndromes" will be used. Sickle cell syndromes are genetically inherited conditions which affect the red blood cells' haemoglobin.

If a person inherits two sickle haemoglobins, one from each parent, they will have a condition called sickle cell anaemia (Hb SS). Where the sickle haemoglobin is inherited with another unusual haemoglobin, for example haemoglobin C, the individual will have sickle haemoglobin C syndrome (Hb SC). If sickle is inherited with beta thalassaemia, the individual will have sickle beta thalassaemia syndrome (Hb SbThal).

These are just three types of the condition known collectively as sickle cell syndromes. Sickle cell anaemia is the most common and often the most severe of the three. In these conditions, the red blood cells lose their ability to carry oxygen properly, the cells become hard, brittle, fragile, break easily, and only live half as long as healthy red blood cells. Therefore, these individuals become anaemic. Sometimes, the red blood cells clog together and block the narrow blood vessels. This gives rise to a severe pain known as "sickle cell crisis". (see Diagram 2)

Diagram 2

People with sickle cell syndromes may experience tiredness, feel lethargic, lose their appetite, are prone to getting infections, and will often become breathless during strenuous exercise.

During a crisis, a person may need to be admitted to hospital for treatment of infection or for relief of pain. Although these episodes are not constant, they are unpredictable in onset and severity.


HOW IS A SICKLE CELL SYNDROME TREATED?

There is no simple cure for sickle cell syndromes. Doctors treat the symptoms if and when they occur. Individuals with this condition can do a lot to prevent symptoms by learning as much as they can about the condition and taking steps to stay healthy.

For example, avoiding damp, cold conditions, taking prescribed medicines, eating a healthy, balanced diet, avoiding smoking, and by seeking prompt medicial care when required. Because the anaemia is not caused by lack of iron, it is important that iron tablets or iron tonics are NOT taken, unless it is prescribed by a doctor.


SO WHAT IS THE DIFFERENCE BETWEEN SICKLE CELL TRAIT AND A SICKLE CELL SYNDROME?

Sickle cell trait (Hb AS) is not a disease or an illness. Because these individuals have one usual haemoglobin A, their red blood cells remain round and healthy. They just carry the unusual sickle haemoglobin gene.

Sickle cell syndrome, on the other hand, can be a serious condition, even though it can affect individuals differently. While some people remain fairly well, others may experience many episodes of pain and discomfort which require hospitalisation.


HOW DO YOU GET A SICKLE CELL SYNDROME?

A person can only get sickle cell trait, or a sickle cell syndrome, from their parents. These conditions cannot be transmitted like an infection; they can only be inherited through the genes. Each parent is born with two haemoglobin genes. Each time a couple are expecting a child, the child will take one haemoglobin gene from each parent to be able to make their own two haemoglobin genes. In each pregnancy, there are always FOUR POSSIBLE combinations of haemoglobin genes that the child can take. These are known as CHANCES. (See Examples of Inheritance)


WHY SHOULD I GET TESTED?

If you wish to find out about your haemoglobin type you can get tested. But it is important, especially when you are planning to have children, or if you need to have an operation where anaesthetic is required.
Talk to your GP, health visitor, school nurse, family planning nurse, social worker, or any health care professional you come into contact with.

It is a simple blood test, which takes only a few minutes, and you get the result in a few days. Your GP can take the blood for testing, or arrange for it to be done at your local hospital. Once you know the exact type of haemoglobin you and your partner have, then you, your GP, nurse, or specialist counsellor can work out exactly which haemoglobin type your children could inherit from both of you.


WHAT IF WE BOTH HAVE SICKLE CELL TRAIT AND WE WANT TO HAVE A BABY?

Since you and your partner have sickle cell trait you have the following options:

• wait until the baby is born to find out what haemoglobin gene the baby has inherited from both of you
  
• have the baby tested in the womb in early pregnancy

Other options:

• adopting a child
• egg or sperm donation

Testing the baby in the womb is called PRENATAL DIAGNOSIS and can be done as early as ten weeks of pregnancy in most cases. The test is done in a hospital. The result is usually available within 2-14 days. This depends on the type of test you are offered.

You can discuss the various options with your GP. midwife, hospital doctor, or specialist at one of the Centres listed (see Centres). They will be able to give you more information, advice, and support to help you and your partner reach a decision.

Prenatal diagnosis is explained in more detail at Prenatal Diagnosis or you can get a leaflet from one of the specialist Centres. You will be given as much information, advice, counselling, and support as you need because this can be an emotionally difficult time.


WHAT DO SICKLE CELL/THALASSAEMIA CENTRES DO?

You may prefer to visit your local sickle cell and thalasaemia centre to have the special blood test done, free of charge. You may wish to visit for more information before deciding whether to be tested, or you may wish for someone to explain your blood test result to you.

Specialist nurse counsellors are available to give information, take blood for testing, or arrange for you to have the test done at your local hospital. Your test result is strictly confidential and wil only be sent to you (and your GP if you wish). The addresses and phone numbers of local centres can be found at Centres.

Staff are available to offer you, your family, friends, and community further information about sickle cell. They can also offer support and advice to people with sickle cell syndromes, whilst they are in hospital, or in their own home and community. Specialist nurses and doctors teach health professionals, non-health professionals, and lay groups, so as to raise peoples' awareness of these conditions and their possible effect on peoples' health, family, and social life.