A little boy is living with a condition so rare his doctors cannot even work out what it is.

Jacob Darley, six, is still undiagnosed after five years of scans and tests, giving him an uncertain future.

Medics know that Jacob has a condition affecting the cells of his body, but they are struggling to pinpoint exactly what is causing it.

They believe he may have two basic genetic problems, a combination so rare, only 12 children in the world have been diagnosed with the same thing.

Jacob's mother Wendy, 42, said waiting for a diagnosis was frustrating but in the meantime the family were determined to get on with their lives.

Jacob is unable to walk, has learning disabilities and has to be fed through a tube.

He has been through numerous tests and procedures, muscle biopsies, MRI scans, blood tests, hip surgery and admissions to hospital with pneumonia.

He needs constant care but despite his problems is always smiling, loves going on trips with his dad Simon, 43, in their Mini and going on rollercoaster rides.

Mrs Darley said: “His condition is degenerative and we have accepted it is a life limiting problem.

“The difficult thing is that because nobody really knows what is wrong, they can't tell us what may happen.

“It is very frustrating.”

The family, from Chichester, are supported by the Chestnut Tree House children's hospice, which provides respite care when they need a break.

Jake has now become one of the hospice's Chestnut Challengers, and has been turned into a cartoon character to help promote the hospice's vital work.