Levi died at 20 months. His mum needs us to know about the test that could have saved him.

Australian parents worried about passing on inherited genetic disorders to their children can now have their babies tested for a wide range of conditions using a simple mouth swab.

Genepath‘s new NextGen test costs $980 to do, but it screens for more than 60 rare genetic disorders linked to a range of cardiovascular, metabolic, neurological, respiratory and muscoskeletal conditions.

It’s news that is very close to the heart of Perth mum Ashley Wibberley, who lost her 20-month-old son Levi in 2015 to Krabbe disease, one of the illnesses that NextGen screens for. While it is too late for Levi, she strongly welcomes the new test to save future Australian babies from suffering her boy’s fate.

Levi was born perfectly healthy in September 2013 and was developing normally. But when he reached six months, something suddenly changed. He couldn’t get up on his hands and knees anymore and he lost interest in his pureed food.

“It was almost like he forgot how to eat. He stopped moving and just lay there,” Ms Wibberley told Mamamia.

“Then the irritability started. The first time we went to emergency he screamed for three days straight.”

Ms Wibberley, 24, and husband Ben rushed Levi to hospital five different times over the course of almost eight weeks but she said she was dismissed as the "young, neurotic, first-time mother", with doctors thinking he simply had severe reflux.

"We weren't getting anywhere. So we decided to pay out of our pockets to take him to a private paediatrician."

It was shortly after this that Levi was diagnosed with Krabbe disease, a rare and difficult-to-diagnose neurological disorder which causes developmental delays. The condition, also known as leukodystrophy, affects the production of myelin, a substance which surrounds and protects the body's nerve fibres.

Treatment for the disease - which children are automatically screened for in the United States but not in Australia - involves bone marrow transplants. The sooner it's treated, the better the chance a child will not only survive, but be cured enough to live a normal life.

"We were very disappointed knowing if they listened to our woes when we first approached then he could have been okay and still with us," Ms Wibberley said.

After his diagnosis, Ms Wibberley shared Levi's battle on Facebook and started campaigning to make genetic testing for rare conditions mandatory .

"Levi has been gone three years now and in those years I've met 12 children with Krabbe disease. That's 12 families that have gone through losing a child that a newborn screening test could have prevented."

She said if the option to run such a test on Levi had been offered to her, she would have done it without thinking twice.

"As a parent you'd never put a dollar value on your child's life."

The NextGen test was developed by Sydney-based pathology practice Genepath to complement the traditional "heel prick" test newborns receive to check for medical conditions including the liver disorder phenylketonuria, cystic fibrosis and hypothyroidism.

Genepath's laboratory director Dr Ben Shum said the new test checks for 50 conditions not currently subject to genetic screening in Australia.

"We can now identify genetic conditions with DNA sequencing before any symptoms become apparent and start treatment or make the necessary lifestyle changes so that, in many cases, those conditions will never become symptomatic," he said.

Clinical geneticist Dr Mary Louise Freckmann said the test represented a good chance for parents to intervene on a disease as early as possible.

"There are conditions like that where you think, 'gosh if I found out that would I want to have that'," Dr Freckmann said.

"And I think that's part of having good information and then the opportunity is there to discuss this with a genetic counsellor before going ahead with treatment."

Dr Freckmann said as technology improves, she expects genetic tests will become more common and hopefully - as costs lower - made available under Medicare.

Ms Wibberley strongly believes the test should be covered by Medicare, and she hopes there will be enough momentum to get the Federal Government behind it.

"Testing a child at birth and figuring out if they have a genetic disorder is in the long run a lot cheaper than supporting a terminally ill child for 12 months in hospital."

But for now, she encourages parents to take the opportunity to take the test and called for greater public awareness of it, with support from doctors.

"Becoming a mother for the first time should be the most joyful experience of your life and you don't always think about the things that could go wrong. But it needs to be thought about," Ms Wibberley said.

To conduct the NextGen test, healthcare professionals or parents can use the mouth swab on a newborn or older child, with the sample then sent to a lab in Australia for analysis based on DNA sequencing.

Once the tests are carried out, the baby's doctor will be sent the results within four weeks so they can discuss them with the parents.

-With AAP