Haemoglobin C

The blood is made up of different parts and each part has a different function. There are red blood cells – they carry oxygen around the body, white blood cells – help the body to fight infection, platelets – clots the blood and stops bleeding and plasma – which is mainly water.

The normal red blood cell is round, soft, spongy and pliable and resembles the shape of a doughnut that has been pressed in the middle slightly. Red blood cells are made in the bone marrow and live for 120 days approximately before they get destroyed and disposed of by the body but the body is constantly making new red blood cells.

The red blood cells contain a substance called haemoglobin, they are like tiny bubbles which combine with the air (oxygen) in the lungs, carry round the body to all the body parts to keep the body tissues and organs alive. Haemoglobin gives blood its red colour when it contains oxygen. These haemoglobin molecules (bubbles) stay freely flowing in the red blood cell, as illustrated in the picture below. There are different types of normal haemoglobin flowing in red blood cell, Adult haemoglobin, Fetal Haemoglobin and minor adult Haemoglobin A2 (A2).

The type of haemoglobin gene which a person has inherited from their parents determines the type of Adult haemoglobin they will have. Genes always come in pairs one from the mother and one from the father. Therefore, every individual inherits two Adult Haemoglobin genes.

The normal and most common haemoglobin gene combination that an individual can inherit from their parents is Haemoglobin AA (Hb AA).

Some people inherit unusual haemoglobins from their parents, for example, Haemoglobin C, which is one of over 1000 unusual haemoglobins found in humans and is a defect of the beta chain.

Haemoglobin C and other unusual haemoglobins are most common among people whose ancestors originate from former and current malaria zones of the world; for example Africa, Asia, the Middle and Far East, Mediterranean islands, and South America. Because of migration and intermarriage, it is also seen in people who did not originate from malaria zones of the world including White Northern Europeans.

Haemoglobin C Trait

Where a person has inherited Haemoglobin A from one parent and Haemoglobin C from the other, they have Haemoglobin C trait, commonly written Hb AC; this individual is considered a ‘healthy carrier’.

  • 1 in every 6 Ghanaians have  C trait
  • 1 in every 30 Other Africans and Caribbeans have  C trait
  • Occasionally seen in White Northern Europeans

The person with Haemoglobin C trait does not have an illness, will not experience any symptoms and his or her health is not affected; this is why a person with Haemoglobin C trait will not know that they carry this unusual haemoglobin unless they have had a special blood test or when they have a child who is later found to have a disease which has been inherited from both parents.

Importance of Haemoglobin C Trait

Although Haemoglobin C trait does not affect the carrier in any way, it is important for them to know that they have this unusual haemoglobin because in the same way that they inherited one haemoglobin A from one of their parents and a Haemoglobin C trait from the other, their children will inherit one haemoglobin from them and the other haemoglobin from their partner. Haemoglobin C trait cannot change into any other form of haemoglobin trait or disease later in life.

If a couple both have Haemoglobin C Trait

If a couple both have Haemoglobin C trait there is a chance that their child can inherit Haemoglobin C disease, which causes a mild to moderate anaemia.

A couple’s children will inherit whichever haemoglobin the parents pass on to the child; to work out how inheritance works see Inheritance of Haemoglobin.

Haemoglobin C inherited with other unusual haemoglobins

Apart from Haemoglobin C there several other unusual haemoglobin genes which if combined with Haemoglobin C can lead to inheritance of a disease, for example, inheritance of Haemoglobin C with Sickle Cell Haemoglobin results in sickle Haemoglobin C disease which is a form of Sickle Cell Disease and may give rise to moderate to a severe anaemia and symptoms of Sickle Cell Disease.

If Haemoglobin C is inherited with other unusual haemoglobin genes the condition is usually clinically mild and does not give rise to any signs or symptoms and the individual will not require any special medical treatment. For example, if Haemoglobin C is inherited with beta Thalassaemia, the individual will have Haemoglobin C Beta Thalassaemia, (Hb CβThal) a very mild disease. For an illustration of how the inheritance works see Inheritance of Haemoglobin.

The Family Connection

Once Haemoglobin C or any other unusual haemoglobin gene has been found in one family member it is important to be aware that other members of the same family may also have the unusual haemoglobin gene. Therefore, it is important to share the information with other family members especially with those who are of child bearing age, planning to get married, start a family or have more children - brother, sisters, aunts, uncles, cousins.

Testing for Haemoglobin C

Anyone who wants to be tested to find out which haemoglobin they have inherited from their parents can visit their GP or contact their local specialist National Sickle Cell / Thalassaemia Centre.