When Lotta Beiny was born, everything seemed normal and she was soon crawling, toddling and doing jigsaw puzzles.

But shortly after her first birthday, she started to lose the ability to move around.

Three-year-old Lotta was finally diagnosed with the genetic condition Rett Syndrome – the disorder that affected Coleen Rooney’s 14-year-old sister Rosie McLoughlin, who died earlier this month.

But Lotta’s 35-year-old parents Bianca Simms and Duncan Beiny, better known as hip-hop “turntablist” DJ Yoda, refuse to give up.

Every day Mrs Simms takes Lotta from their home in Chesterford Road, Hampstead, to Hampstead Heath, holding her by the hands or supporting her back so she can take her own careful steps.

And when they are not walking on the Heath, Mrs Simms is swimming with Lotta in the lido, manipulating her limbs in physiotherapy or taking her to music therapy sessions run by the charity Nordoff Robbins, where her parents see precious flashes of recognition.

Now her family is calling on people to help raise the money needed to find a cure for the brain disorder that affects one in 12,000 girls.

Scientists have already had success in mice with artificially-engineered Rett Syndrome – arresting the start of symptoms with bone marrow transplants and reversing severe symptoms by reactivating the affected gene.

And campaigners are confident that researchers will soon have a similar breakthrough in humans.

Hazel Beiny, 59, Lotta’s grandmother, said: “Bianca had a normal pregnancy and Lotta was born on March 29 at University College Hospital. Everything was absolutely wonderful.

“But after a year to 15 months, Lotta was losing some of her milestones. She had already sat up, crawled and toddled.

“But she was losing the use of her hands, she had stopped crawling and moving around, and eye contact and communication was going. If you have a baby, this is your worst scenario.

“It is believed these girls understand everything but that they are not in control of their speech or their movements.”

Rett Syndrome is caused by a mutation in a gene on the X chromosome, which means that an essential protein is not produced.

Sufferers have normally started to crawl, walk or even talk but they soon start to lose the ability to move and communicate, and end up requiring 24-hour care and are often fed through a tube.

Complications can include seizures, digestive and cardiac problems, curvature of the spine and sudden death.

Sufferers are predominantly girls, while boys who are affected normally die around birth.

But while Lotta’s family were told there was nothing that could be done, Mrs Simms found a “very different story” when she started looking at the latest research.

She said: “It’s a single gene disorder and they have had a tremendous breakthrough in mice.”

Mrs Simms believes that although Lotta’s brain is not functioning properly, it is not inherently damaged and that if scientists could find a way to reactivate the damaged gene or give her the missing protein, she would return to health. She said: “There is a cure. It just needs money.”

Rachael Bloom, executive director of the Rett Syndrome Research Trust UK, whose daughter Amber Dine, 17, is a sufferer, added: “This is a horrendous condition. But it does look so imminently treatable. We just need money to move things forward. Our goal is to raise £1million a year.”

* To find out more, visit www.reverserett.org.uk