Imagine feeling as though you are bursting at the seams with the desire to say something important, but are unable to speak. That has been daily life for Abigail Lishomwa.
The six-year-old cannot call out to her parents, ask her teachers questions or greet other children at the playground.
She has been diagnosed with Rett syndrome — a rare genetic disorder that has effectively silenced her and has caused incredible developmental challenges with movement and dexterity.
Rett syndrome has impacted every aspect of Abigail's life, but the young girl has a big personality and has found ways to communicate.
"When you have someone who is nonverbal, it's very easy to forget that they do have a voice. It may be inside them, but they have it," Ms Lishomwa said.
"She's so clever. I just can't imagine the level of frustration she goes through."
A syndrome that can 'appear from nowhere' after the age of one
Abigail's syndrome caught her family by surprise.
"I remember our 12-month check-up with Abigail," Ms Lishomwa said.
"Everything was fine. She was ticking all of the boxes. She was a little bit of a late walker, but other than that, we had no concerns. The doctors had no concerns.
She said Abigail stopped "babbling", no longer making typical baby sounds.
Other symptoms included no eye contact, no longer being able to use her hands, and repetitive movements such as pacing.
"Our diagnosis started off as autism and we hit early intervention therapy pretty hard, but sort of didn't see the changes we were expecting," Ms Lishomwa said.
"So, we ended up having the genetic test which confirmed Abigail had Rett syndrome.
"I'm not going to lie, I was devastated.
Rett syndrome can present as 'cocktail of symptoms'
Claude Buda became president of Rett Syndrome Association of Australia after his 11-year-old daughter Annelise was diagnosed with the disorder in 2012.
He explained that many symptoms associated with Rett syndrome overlapped with other conditions — and that often led to misdiagnosis.
"Autism, Parkinson's disease, epilepsy, anxiety disorders, and cerebral palsy all rolled into one person — all those symptoms manifest and take over the child's life when they have Rett syndrome," Mr Buda said.
"Even among doctors, not many of them have heard of Rett syndrome. So we're trying to raise awareness so children can be diagnosed and treated properly."
Ms Lishomwa has also become a strong advocate of promoting awareness, launching a campaign called Speechless for Rett syndrome, which challenges people to avoid speech and other communication for 24 hours.
"Think about what it would mean to not be able to talk, not be able to type, to text. How it would feel to be stuck in your body knowing exactly what you want to say and have no way to say it," Ms Lishomwa said.
Girls more likely than boys to develop Rett syndrome
Clinical geneticist at the Sydney Children's Hospital Carolyn Ellaway said the gene for Rett syndrome had been located on one of the X chromosomes.
"Boys only have one X chromosome, so for them to have a change in the Rett syndrome gene means that their features will be much more severe than girls, and so often those pregnancies do not go to term," Dr Ellaway said.
"In Rett syndrome, the structure of the brain is essentially normal, but it's just not functioning normally.
Dr Ellaway added that the fact that affected babies developed "normally" for their first year or months meant perhaps there was a "window of opportunity" to intervene or reverse symptoms.
However, the cause of Rett syndrome has remained a mystery and a cure has not been discovered.
How a mysterious letter changed Abigail's life
Although Abigail faces daily challenges, there have been plenty of happy moments since her diagnosis.
Ms Lishomwa said she recently checked the letterbox and discovered her daughter had been sent an anonymous letter.
"Inside was a note addressed to Abigail, saying how enchanting she was, how this person couldn't wait to hear what she had to say," Ms Lishomwa said.
"And behind that note was a bank cheque for $13,000. That money was specifically for Abigail to buy an eye gaze communication device."
The device allows users to select symbols and words on a screen with their eyes before the machine vocalises the message.
Her parents had planned to hire the expensive assisted technology, but thanks to the anonymous donor, they were able to ring the supplier and pay for it in full.
