Lara's legacy: Widening the search for a 'genetic twin'

Lara Casalotti spent Christmas in hospital after being diagnosed with leukaemia

A drive to find a stem cell donor for a mixed-race student has been successful - but what impact will it have for others waiting for a "genetic twin" to save their life?

Lara Casalotti, 24, is part-Chinese, part-Thai and part-Italian.

People who are black, Asian or mixed-race are far less likely to find a match than a white northern European, so a celebrity-backed viral campaign (Match4Lara) was started by the Casalotti family.

Within weeks, a match was found. But perhaps more importantly, people who turned out not to be a match signed up to the register too.

Is this significant?

Since the beginning of the Match4Lara campaign more than 15,600 people have joined the Anthony Nolan register.

This compares to 4,135 during the same period last year - a 277% overall increase.

The has also been a sharp increase of black, Asian and mixed-race donors signing up during this period - 684% higher than the same period last year.

How difficult is it to find a match?

It is hoped the donor, who remains anonymous, will donate their stem cells in March.

According to Jack Wilson at Anthony Nolan, a complete match with a stranger is "like gold dust".

"It's incredible to think there could be someone on the register who is essentially your genetic twin," he said.

"It doesn't mean they have exactly the same background or heritage as you - for example Lara's match may have been someone part-Chinese, part-Thai and part-Spanish. But it's really special and personal thing to have a match."

Currently, about 60% of patients find a perfect match - often with a sibling - and while partial matches can be considered they are not as successful.

But that 60% drops to just 20% when the patient is of black, Asian or mixed ethnicity.

There are a few potential reasons for this - the vast majority of donors registered are white, northern Europeans, so matching stem cells simply cannot be found.

According to NHS figures there are three times as many white people registered as all the black, Asian and mixed-race donors put together.

Another reason for the difficulty is that a mixed heritage is likely to be more complex than one which is completely one race - which further narrows down potential matches.

Why do so few black, Asian and mixed-race people register?

In the words of Mr Wilson: "If we knew the answer to that, we could tackle it."

But he suggested that in some ethnic groups there "may be more barriers" to signing up.

"In some communities, older people are very influential and many people still have outdated information about the donation process, which may be off-putting. People don't seem to realise how very easy it is."

He also suggested a general lack of awareness in all demographics.

"People think it will be very painful.

"But most donors tell us it's surprisingly simple and similar to a blood donation, but takes a little bit longer - about four hours. Plus you can register all online and it's all completely free," he said.

What makes a match?

Matching is based on human leukocyte anitgen (HLA) tissue type. HLA is an individual genetic characteristic inherited from each parent.

It is similar to blood groups, but more diverse and complicated.

HLA is made up of genes and to find a match, experts look at five key sites. Each of the sites has two alleles (types of genes) making 10 in total.

The genes are compared to those of donors. If all 10 match then it is a 10/10 match.

When it comes to finding a match, the higher the better, because bodies need to recognise and accept the donor's stem cells.

If the genes do not match, the body will treat them as intruders and reject them.

Source: Anthony Nolan Trust

What sort of impact will Lara's campaign have?

According to the Anthony Nolan Trust, although it is too soon to see a direct impact from the surge in registries, in the coming months and years there will be "a massive" effect.

"Any one of those people would be a match for someone in the future," said Mr Wilson. "And remember, you're not just saving the person who needs a transplant - in many ways you're saving their loved ones too.

"The odds are, if you register, you won't be called - it's quite rare. But 2,000 people need a transplant every year - and you could be their lifeline, which is quite incredible really."

Recruitment events organised by the Casalotti family which were scheduled for later this year will still go ahead, encouraging more mixed-race donors to sign up.

If the trend continues, Lara's legacy could be more than simply her own recovery.