Hidden black ancestry linked to rise in sickle cell blood disorder

Increasing numbers of white babies are born each year carrying the sickle cell anaemia trait because of hidden black ancestry, according to a leading geneticist.

Increasing numbers of white babies are born each year carrying the sickle cell anaemia trait because of hidden black ancestry, according to a leading geneticist.

Extrapolating from 16th century census data, Dr Steve Jones, of University College London, has calculated that one in five Britons, 11 million people, have a black ancestor. People who think of themselves as white but have the sickle cell trait almost certainly had a black ancestor, he said.

Sickle cell anaemia is an inherited blood disorder that causes anaemia and chronic pain. People who inherit the disorder have two copies of the sickle cell gene, one from each parent. If both parents are carriers, having just one copy each, there is a one in four chance of the child picking up two copies of the gene. Those who carry just one copy have the sickle cell trait but have no symptoms and have the advantage of being protected against malaria.

One in four people in West Africa carry a copy of the gene, as do one in 10 Afro-Caribbeans. It is very rare in white Caucasians. In Britain, 12,000 people have the disorder.

"When people moved out of West Africa, the sickle cell gene moved with them. As a result there are probably hundreds of thousands of people who think of themselves as white and indeed have white skins, who are carriers of the sickle cell gene. So there is an increased prevalence of the gene," Dr Jones said.

Claire Thompson, health education officer for the Sickle Cell Society, said: "The increasing number of mixed race relationships means that the disorder is moving across into the white population, who do not know they are carriers. This is leading to an increased prevalence of both carriers and people suffering from the disorder." Ms Thompson said there was no national screening programme. "It has been seen as a black issue but increasingly white people are carriers."

A white mother and daughter from Liverpool, Valerie Pollard and Jayne Prior, found that they carry the trait after Mrs Prior, a 35-year-old trainee accountant living in Brighton, received a letter from the National Blood Transfusion Service saying that they had tested her donated blood and found the sickle cell trait.

"The first thing I did when I found out was telephone my mother, she went to get tested and was also found to be a carrier," said Mrs Prior.

The pair, who appear in the Channel 4 series Britain's Slave Trade tomorrow, have traced their ancestry back to a Jamaican sailor who settled in Liverpool in the 18th century.

Mrs Prior said: "Thinking there might be that history in our own family suddenly makes you think about it [the slave trade] more and how it's had a knock-on effect to a lot more people than they probably realise or want to realise."

What is sickle cell anaemia?

Sickle cell anaemia is an inherited blood disorder characterised by chronic anaemia and periodic pain, plus the risk of stroke and heart attack. The underlying problem is that one component of the red blood cells, haemoglobin - which carries oxygen - is defective. This results in the usually doughnut-shaped cells becoming sickle-shaped. These are unable to squeeze through small blood vessels, causing blockages that deprive organs and tissues of blood.