The family of a girl who broke her leg at school are to sue the local authority, claiming the injury led to her death.
Wheelchair-bound Chloe Sturgess, 13, snapped her thigh bone in a lesson at Downs View Special School last year.
While she was in hospital she picked up a series of chest infections and later died of an asthma attack.
Mother Denise Rawlins said she believed the injury had shortened Chloe's life expectancy.
She said: "I am angry. No-one has taken any responsibility.
"I have got a big hole in my life now.
"I believe this put in train the set of events that led to her death."
The family is taking legal action against Brighton and Hove City Council, who manage the Woodingdean school, claiming her injury was due to negligence by staff.
Another pupil is thought to have broken Chloe's leg by picking it up and crossing it over the other.
Because of her condition her limbs were stiff and the bone snapped above the kneecap.
Her family believes there was only one teacher present with the six pupils at the time, although five members of staff were allocated to the class.
They say they have been told four of the workers took their break at the same time.
Chloe's severe disability meant she required one-to-one attention.
She suffered from Rett Syndrome, a rare genetic illness which stops children developing.
The condition, which normally affects girls, meant she was unable to speak, walk or crawl.
She lived with Miss Rawlins, her father Mark Sturgess, 37, and her nine-year-old brother Wesley at their home in Collingwood Close, Peacehaven.
The broken leg she suffered at Downs View left her needing operations to insert two pins and two rods in her femur.
She spent six weeks in the Royal Alexandra Children's Hospital in Brighton.
But while she was there her respiratory problems worsened and she suffered three chest infections.
On April 10 she died after a severe asthma attack.
Doctors had earlier told them they could expect Chloe to live to between 15 and 20 years old.
Her family have now launched a legal action against the school over the incident.
Miss Rawlins, 38, said: "We'd like to see action being taken against staff at the school.
"If it happened to Chloe it could happen to another kid.
"We are suing so this can't happen to someone else."
The family's solicitor, negligence specialist Warren Moore, said: "We are bringing this case against Downs View School, that they were negligent to leave one person looking after these special needs students when there should have been five people."
He said he has exchanged letters with the council and expects to file a court claim later this summer.
The solicitor says the council has replied that the incident was unforeseeable and the pupil who injured Chloe acted without malice.
Downs View Special School, in Warren Road, is a school for pupils with severe and multiple learning difficulties and autism.
At its last inspection it had 79 children aged four to 16 on its roll.
An Ofsted report of the visit in May last year - the same month as Chloe's accident - rated the school as "good", and said pupils' personal development was "outstanding".
It said: "The care, welfare and guidance provided by the staff are of a very high quality.
A spokeswoman for Brighton and Hove City Council said: "The council was sorry to learn of Chloe Sturgess' death.
"However, as a claim has been made by Chloe's family and is ongoing it would be inappropriate to comment at this stage."
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