A Bromley man is to take on a 100km Ultramarathon this month to raise funds for his nephew with a rare genetic disorder.

Sidney Cooke from Yalding, Kent, aged three, was diagnosed with the rare genetic disorder type one spinal muscular atrophy (SMA) four months after birth.

He was treated with the £1.8m single dose of gene therapy Zolgensma – the most expensive drug in the world – shortly afterwards. Before this drug was made available, children with this disorder typically survived less than two years.

There is still no cure for SMA, but drugs and therapies help manage the condition and improve strength and flexibility. However, most therapies and much of the equipment needed is not available on the NHS, and families have to privately fund to cover what is needed so fundraising is inevitable for most families in this circumstance, given the extent of therapies needed is very expensive.

Dean Cooke, 37, an emergency gas engineer, will be running from Richmond to Brighton on May 25 – a distance of 100km. He said:

‘I’ve run marathons in the past – I usually run 60 to 80 miles a month – but running it all in one go is a different matter!’

‘I’ve been training since January and the longest run I’ve done so far is 45 miles. I’ll be starting the race at 7:30am and if I finish while it’s still light, I’ll be happy!’

‘Sid’s parents have to raise money constantly – I’m glad to be able to do something to help.’

Sidney’s mum Sophie, 35, said: ‘Every piece of equipment typically costs thousands, even if we manage to buy it second hand, and obviously he is always growing and his needs are always changing.’

‘He is coming on leaps and bounds, but his progress relies on us being able to fund equipment and therapies to enable it.’

‘Currently we are trying to fundraise for house adaptions. I am now really struggling to carry Sidney up and down the stairs and dress him etc, so we have started the process of getting a through floor lift and having a specially adapted bathroom made, which involves extending his current bedroom (doing an extension) to make this happens. Of course this is not all covered by government money, so we are going to have to fundraise an extra circa £40k to make this happen.’

‘So far we have raised more than £14,000 to help pay for therapy and equipment – there’s no way we could have done this without our friends, family and supporters.’

Sidney’s family is being supported by children’s charity Tree of Hope which helps families fundraise for children like Sidney with healthcare needs and provides charity status to benefit from gift aid, corporate support while also providing donor reassurance.

Tree of Hope CEO Becky Andrew said: ‘We’re really pleased to be supporting Sidney’s family to ensure he gets the support he needs and we wish Dean all the best with the ultramarathon.’

To sponsor Dean or to donate to Sidney’s fund visit: https://www.treeofhope.org.uk/ways-to-give/childrens-campaigns/help-super-sid-fight-sma-type-1/ or https://www.justgiving.com/fundraising/ultramarathon-supersidneycooke