The father of a desperately sick tot who needs lifesaving surgery has compared the chances of finding the perfect match as "like winning the lottery".

Evie Sanassy, from Rochester, has a rare blood disorder and needs a stem cell transplant to survive.

But because the 15-month-old's parents are of mixed heritage, tracking down an ideal donor has so far proved fruitless - and time is fast running out.

Evie is currently at Great Ormond Street Hospital in London undergoing a gruelling programme of chemotherapy, her parents Daven and Rouku Sanassy by her bedside.

The couple come from Mauritian, Sri Lankan and South Indian roots and the majority of research networks deal with British and European sources.

Dad Daven, 40, is urging people from South Asian backgrounds to enrol on to the stem cell register to give their only child the chance of life.

Evie, whom he describes as "cheerful and tough", has Still's disease, a type of arthritis and Macrophage Activation Syndrome, a severe form of chronic rheumatic disease.

Her condition severely affects her immune system and the only way to keep it under control is to have the transplant.

Her parents are currently renting accommodation in London while Evie has four hourly sessions of chemo.

She fell ill in October while on a visit to Mauritius to meet her grandparents and had to be airlifted to a hospital in South Africa.

Daven said: "The chemo acts like a blunt instrument attacking her system, but there's only so much chemo she can take.

"It looks by the autumn we might have to settle for an imperfect match.

Daven, a chief technology officer and Rouka, 35, a ceramicist, have been carrying out their own research and he has put out an appeal on social media.

He said: "People of South Asian heritage are underrepresented on the register so please encourage anyone you know to join.

"A spit sample is all that's needed to join the register, and an actual life saving donation is a similar process to donating blood.

"Finding a match is like winning the lottery: even if you're not a match for Evie, you could save the life of your genetic doppelgänger one day."

The Anthony Nolan blood cancer charity is trawling a worldwide network of registers to find a match for Evie.

Henny Braund, chief executive, said: "After being told that your child needs a lifesaving transplant it can be devastating to be told that not only are you not a match but that the chances of finding a perfect match are significantly lower because of their heritage.

"My heart goes out to Evie and her family as they await news and Anthony Nolan will support them every step of the way.

"Ethnicity can determine who can receive a stem cell transplant. We’re working hard to stop this from happening, and are calling on young people aged 16-30 from South Asian backgrounds to join the register.

"One day you could be matched to a patient in need of a lifesaving stem cell transplant and bring hope to a family like Evie’s."