Her spine being at such a degree of curvature means her heart and left lung are shutting down, no longer able to cope with the stress and pressure being applied by the spine.
The bright and bubbly Kati, who loves playing Lego with her brother and going to the beach with the family's dogs, is constantly in crippling pain.
"Her skeleton is really fragile and a lot smaller than it should be but other than that they haven't been able to define it as one thing," Kati's mother Esther Allen explains.
"Every day for Kati is a struggle.
"She's been under a genetic team in Wellington and, with all their testing, they haven't found anyone in New Zealand to match her or to match her to any other kind of syndrome in New Zealand.
"Specialists are pulling aspects from different syndromes that are known, pulling little bits and pieces such as the fragile bones and the scoliosis of the spine together, creating a Kati syndrome."
The future is unknown but the first step is talking to doctors at Boston Children's Hospital in Massachusetts, USA who are specialists in spinal issues.
"We have all kinds of questions that we really want answers to, and with Boston being the leading hospital in spinal care for children, dealing with more than 9000 paediatric spinal patients each year we hope they'll have some answers to our questions."
With a much larger population Esther is hoping they've had similar cases to Kati's, however getting a Skype consultation costs US$650.
At the moment the best option is surgery to straighten out Kati's spine.
With 50-100 per cent chance of having severe complications, Esther has to pick the best option out of the worst case situation.
"It's a really tough call as a mum.
"You just want to do what's best for your child.
"Without the surgery on her spine Kati faces her heart and left lung having severe damage and failure.
"Either way it's hard. It's a lose-lose situation."
After six years of doing it on their own, Esther is finally asking for financial help, creating a Givealittle page.
Travelling to and from appointments and specialists while constantly looking after Kati is a huge financial burden on the single-income family.
With Boston prepared to do the Skype consultation, that is just the start.
"Kati has such a magical personality and she has gone through so much.
"We need to raise money for the consultation and all the other costs that come with the travel and surgeries in future.
"We just love her so much. Kati needs your help."
To help Kati and her family visit Kati's Givealittle page
