John Henderson (73) today begins his bid to pedal across nine islands in the Outer Hebrides in aid of five-year-old Redding girl Emma Garioch.
The youngster was diagnosed with the neurological disorder as a toddler, meaning she cannot walk and is locked in a body which does not obey signals from her brain.
Although Emma was born a happy, healthy baby in October 2013, mum Alison and dad Stuart noticed she had some delays in her development by the time she was nine months old.
Despite being reassured by doctors, the family continued to seek medical advice and in December 2016 Emma was diagnosed with Rett Syndrome.
Researchers from the University of Edinburgh are working towards a cure for Rett Syndrome by using genetic engineering to replace a missing protein.
Experiments on mice made the symptoms of the condition disappear and human clinical trials are due to start later this year.
Emma’s grandad John is hoping his daring cycling challenge will raise at least £1000 for UK charity ReverseRett.
The charity was set up nine years ago by families who wanted to support the US non-profit Rett Syndrome Research Trust organisation, which believes in the prospect of a cure.
So far, UK contributors have raised more than £2 million.
John’s mission will take him to the southern tip of Vatersay through Barra to Eriskay and then on to South Uist, Benbecula, North Uist, Berneray and over to Harris and Lewis before finishing at the Butt of Lewis hopefully for Sunday.
He said: “As a family we believe it is important to highlight and support ReverseRett in any way we can especially as a cure is in sight.
“The first clinical trial of gene therapy on a girl with Rett Syndrome is imminent.
“As ever, funding is the key and we need to keep the donations coming in if we are to set our children free.”
Rett Syndrome affects girls around the age of 12 to 18 months.
It is estimated to happen to one in 10,000 children and is rarely found in boys.
Children with Rett are unable to walk or use their hands and often deal with breathing problems, feeding tubes, seizures, anxiety and gastrointestinal and orthopaedic issues.
Research has shown children with Rett Syndrome have no brain damage and understand more than their bodies allow them to show.
To donate to John’s fundraising efforts, click here.