Some doctors in rural areas are having to apply for extra funding in order to diagnose patients with autism, the Royal College of GPs has said. The BBC's Victoria Derbyshire programme has spoken to families with autistic children who are struggling to cope with their violent outbursts.
Jamie punches his mum and spits in her face while she cries, in footage captured on a tablet.
The seven-year-old has a rare form of autism called pathological demand avoidance (PDA), meaning a simple request to do something can lead to a violent meltdown lasting for hours.
The behaviour is not the fault of the children with PDA, as it is the condition that prompts them to behave this way. In some cases, they do not know what they are doing.
In the incident captured on video, Jamie is stressed as he does not want to go to school.
"I get very, very, mad and smash stuff," he says.
His mum, Kate, from Bury St Edmunds - whose surname we are not using - says during violent episodes, he smashes up the house and has tried to attack her with knives.
She finds the video footage traumatic and hard to explain.
"Part of me can't believe that is my child, because we have really good times," she says. "My main concern is he is a risk to himself when he gets like that. He is not in control whatsoever."
Some local authorities do not clinically recognise PDA - meaning children like Jamie with the condition often do not get the support others with autism receive.
Jamie, who also has attention deficit hyperactivity disorder (ADHD), was aged just three when he started becoming violent and six when he was diagnosed with PDA.
The long wait for his diagnosis caused Kate - who is now a single mum - to spend nearly £10,000 on a private consultation.
"If my son had a more outward diagnosis, so if he had severe autism, I think we would have got help," she says.
According to the NHS, Jamie is one of 700,000 people in the UK with autism.
GPs are usually the first point of contact when it comes to recognising the condition.
But there are concerns that doctors in rural areas have to ask for extra money to refer patients for diagnosis.
Dr Carole Buckley, from the Royal College of GPs, tells the Victoria Derbyshire programme: "We don't have to get exceptional funding for heart disease, cancer, diabetes or depression. Why on Earth should we have to get exceptional funding for an autism diagnosis?"
A study of 1,200 parents by the PDA Society found 80% often experienced challenging behaviour from their child.
But many are not violent.
Dr Buckley says early intervention is key, with evidence suggesting most of the children who demonstrate challenging behaviour at nine still demonstrate such behaviour at 19 and 29.
National guidelines state the process of diagnosis should start within three months of being referred.
But the National Autistic Society says some children can wait "many months, sometimes even years, for a diagnosis and support, just because of the poor or overstretched services where they live".
Ten-year-old Kierney's family say they need more support. She is autistic and has also been diagnosed with PDA, as well as multiple anxiety disorder and depression.
Like many children with PDA, she is affected by the negative consequences of the condition as much as her family.
She often struggles to communicate - and when she becomes frustrated, the family home can become a place of chaos and violence.
Black eyes, bites, and scratches are just some of the injuries Kierney has inflicted on Erika, her mum. And there are times when the police have even had to be called to calm her down.
"I feel really bad when I hurt my mum and I don't want to hurt her," she says. "What I do to her makes me feel really upset and embarrassed."
She thinks she would be able to stop being violent if she got the right support.
"If not, I think I will end up getting arrested, which I don't want to happen. I just want to stay with my family and be happy."
Erika has had to give up work due to her daughter's condition, which she says has been made harder by social services, who have struggled to provide regular respite care.
"Children's services have said numerous times there is nothing they can do to improve or change our situation," she says.
East Sussex County Council says it has not been able to find a suitable carer since 2016, due to a shortage of care workers for children with additional needs in the area.
"It's not always possible to find the services parents want or need," a spokesman said, adding that they "will continue to look at options with families".
Lib Dem MP Norman Lamb, former Care and Support Minister, says the government and NHS are failing families who are not being properly supported by their local authorities.
"In a way we are abandoning families to try to cope on their own with extraordinary complex circumstances and that's really unacceptable," he says.
"This is a human rights issue because we are failing people in terms of their rights to a family life and to have opportunities in life."
He plans to raise the issue in Parliament.
A NHS England spokesman said services for young people's mental health had increased and improved significantly in recent years, giving an extra 70,000 children access to care.
"The long-term plan for the NHS will have young people's mental health front and centre, including building on the £7m investment in young people's crisis care, developing more services in the community and in people's homes to avoid hospital admissions, and working with local authorities."