Distraught parents have told how their son is slowly being poisoned by his own brain.
Blighted by a fatal neurological disorder, four-year-old Morgan Mawson is unlikely to make it to his tenth birthday and is unable to walk or talk.
He is one of 200 children in the UK who have infantile Batten's disease which is so rare his parents' chance of meeting and conceiving him was only one in two billion.
Both Jenni, 28, and Eddie, 37, from Derby are carriers of the faulty gene which causes Batten's disease - meaning any of their children have a one in four chance of inheriting the condition.
At birth there are no symptoms of the disorder so it was only when Morgan failed to develop properly that his parents realised there was something wrong.
Doctors told the devastated couple that he was not expected to reach his tenth birthday and that a deadly bodily poison was slowly destroying his brain.
Jenni said: “His brain produces a chemical which can be poisonous but Morgan is missing an enzyme which dissolves it - so that poison is killing off his brain.”
“It's killing off his nerves in his arms, legs and mouth - it stops him from being able to chew and talking properly.”
“His behaviour is regressing. At the moment he wants to throw things everywhere and he wants to put things in his mouth. It's like we've gone back to the baby stage.”
Eddie and Jenni have had to quit their jobs to act as full time carers for their children.