Her mother, Kathy, just had a feeling, call it mother's intuition, that something was not right with her second-born daughter. 

When the Miner’s Rest infant was admitted to hospital at 14 months, the nurses were very concerned that she was not making enough sounds.

By the time she was four or five, she could still only string a few words together.

Kathy said while she noticed that her daughter was able to recognise letter and words, she struggled to verbally communicate what she felt.

"She went to kinder knowing all her colours and taught the other children their colours and how to sign their colours," she said.

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It was not until Madilyn was about to start school in 2006 that researchers finally discovered the source of the problem, a deleted segment of chromosome 17 called it Koolen-de Vries syndrome.

Now breakthrough Australian research published in The European Journal of Human Genetics has found that, despite some children with Koolen-de Vries not saying their first word until age seven, they should eventually learn to speak intelligibly.  

About 1 in 16,000 people worldwide are estimated to be affected by Koolen-de Vries, including approximately 300 Australian children.

The study found that while most of these children did not say their first words until around two or three, or even later, "remarkably" most will be able to speak by eight to 11 years.

 "It is a really lovely, good news message," said the paper's co-author, Angela Morgan, a professor of speech pathology at the Murdoch Children's Research Institute.

"Later in primary school it does mean that the children will be able to develop speech. The parents are there waiting, desperately hoping that their kid is going to speak. Until this paper came out they didn't have any idea of the future prognosis."

About 1 in 16,000 people worldwide are estimated to be affected by Koolen-de Vries, and 300 Australian children.

While the disorder is marked by developmental delay and mild to moderate intellectual disability, the children are described as cheerful, sociable and cooperative. 

The study showed the need for children with Koolen-de Vries to have speech therapy early in life.

Madilyn is now 15 and attends the Ballarat Specialist School. 

She loves sports, colouring, singing the songs out of Mamma Mia! and slapstick comedy. 

The Hunt family spent many years anxiously waiting for her to speak.

"We so desperately wanted her to speak," Kathy said. 

"And now we have trouble getting her to not speak."