It has been discovered Grace, now aged 9, has Coffin-Siris syndrome, a rare genetic condition affecting about 80 people worldwide.
''The answer explains a lot. Now we know, we can start to work with it,'' Mr Hughes said.
Grace first featured in the Otago Daily Times in 2009 as a 5-year-old who did not eat and had to be tube-fed as a result.
Doctors found no physical reason for her inability to eat and after years of hospital visits her parents decided to take the momentous step of taking her to a specialist hospital in Graz, Austria.
With the help of family, friends and the public, $50,000 was raised to enable the family to travel to Europe for treatment.
Grace returned from Austria having moved on to eating custard and without the gastric tube which had been keeping her alive.
It meant she could start school, which she loved, although she continued with counselling and speech therapy.
The diagnosis came after a Swiss geneticist discovered the gene anomaly indicating the syndrome. Mr and Mrs Hughes' and Grace's blood was sent to Europe and included in the trial.
It confirmed Grace had Coffin-Siris syndrome, something that had been considered by doctors in Austria but rejected, as she did not have what had been thought to be the key feature of the disease - abnormalities of the fifth (little) fingers or toes.
It was a relief for her parents, who now had others they could speak to about handling Grace's condition and had confirmation there was a reason she did not want to eat.
''There were people who thought she was just a fussy eater, but we now know it's part of her make-up. She's not just being naughty,'' Mrs Hughes said.
However, because she had not been diagnosed, her parents admit they had probably pushed her harder than they might have if they had known.
''Because we were told there was no physical reason, we did everything possible. We did not accept 'no','' she said.
As a result, Grace was walking and eating without a tube, something most children with the condition did not do.
Custard was still Grace's favourite food, but she also ate food processed into a paste, yoghurt and ice cream. A dentist had found her mouth structure meant it was hard for her to chew.
''She'll eat what we have, just without any lumps.''
They were slowly increasing the texture and temperature of her food and doing exercises to help her get over her fear of crunchy food.
She was doing well at school with the help of a teacher aide and often surprised her therapists with her achievements, she said.
''Grace is tiny, but that is a blessing. She has a really motherly nature and is very sensitive to other people's emotions,'' Mrs Hughes said.
Coffin-Siris syndrome: Characteristics of the syndrome include. -
• Difficulty feeding.
• Inability to gain weight.
• Developmental disabilities.
• Short stature.
• Mobility problems.
• Abnormalities of the little fingers and toes.
