Leo Yang is 10 months old and has Down syndrome and leukaemia. In a matter of weeks, his Chinese mother — the only family he has — will be deported, unless Home Affairs Minister Peter Dutton intervenes.

Key points: Leo has Down syndrome and leukaemia and has no other family in Australia

Leo has Down syndrome and leukaemia and has no other family in Australia His mother Sarah faces deportation to China because she has been denied a carer's visa

His mother Sarah faces deportation to China because she has been denied a carer's visa Advocates say the boy will almost certainly end up in foster care which could jeopardise his treatment

"I love Leo, I want to stay with him," said Leo's mother Sarah Yang*.

"I haven't put all my hopes on [intervention] because I don't want to feel too disappointed in the end if I find out things don't work well."

Life has taught Ms Yang to not get her hopes up.

Ten months ago she was in what she thought was a loving, long-term relationship with an Australian man, Leo's father.

She had been living in Australia on a student visa since arriving from China in 2013 and the couple were preparing to have their first child together.

'He's my angel'

An hour or so after Leo was born, he was diagnosed with Down syndrome.

The father stuck around long enough to sign the birth certificate — ensuring Leo's status as an Australian citizen — but promptly disappeared from their lives.

Leo may be eligible to live in China, where one Down syndrome advocate says he would face greater "stigma" due to his condition. ( ABC News: Danielle Bonica )

There were more blows to come.

In January, when Leo was six months old, Ms Yang took him to hospital after noticing small red spots on his arm.

He has been in hospital ever since, as he continues to get treatment for acute myeloid leukaemia.

He now faces the prospect of losing his mum.

"I was told by some midwives that babies with Down syndrome are like angels from God," Ms Yang said.

"I don't have religious beliefs, but I believe he's my angel."

Ms Yang applied for a carer's visa that would allow her to stay and look after Leo, but this has been rejected.

Under Australia's immigration laws, a 10-month-old child with Down syndrome and leukaemia does not meet the minimum threshold of needing a carer.

'Dreadful' that boy will be denied his mother

The case has passed through the Home Affairs Department, the Administrative Appeals Tribunal and a final appeal now rests with the Minister.

If the decision is not overturned, Ms Yang will be deported and Leo will almost certainly end up in foster care.

Adoption rates in Australia are low and children with special needs are even less likely to be taken in.

"To consider that this child might be denied access to his mother when he's got no-one else to support him is just dreadful," said Dr Jan Gothard, a health and disability specialist with Estrin Saul Lawyers, which has taken Ms Yang's case on a pro-bono basis.

Sarah Yang said baby Leo was her "sunshine" and kept her from getting depressed. ( ABC News: Danielle Bonica )

Dr Gothard said this "devastating outcome" was inevitable given the restrictive nature of the current regulations to determine eligibility for a carer's visa.

"The notion that a little boy with no other family support doesn't meet the requirements for a carer's visa is very flawed," she said.

"That matrix doesn't take into account social circumstances, it's just a set of numbers, a table to be filled in and if somebody doesn't meet that then they are rejected."

She said there was still ample scope for Mr Dutton to intervene.

"The primary plank of welfare policy relating to the wellbeing of children is to try and preserve the family unit," she said.

"In this family's circumstances, denying Sarah a permanent visa to stay in Australia and care for her son, who is a vulnerable child in obvious need of care and protection, is a violation of this first principle."

Down Syndrome Australia has thrown its support behind Ms Yang's case.

"Any child at that age needs a significant amount of care … certainly a child who has Down syndrome and leukaemia needs a lot of care and a lot of support," said the organisation's chief executive, Ellen Skladzien.

"I think it would be a very reasonable thing to provide her with a carer visa."

Staying in Australia a better outcome

In a letter to the Administrative Appeals Tribunal, one of Leo's doctors warned that "… the removal of a child's primary attachment figure impairs their ability to form bonds, regulate emotions and manage stress later in life".

The letter noted that Leo's mother "… has been at his bedside and is his primary, in fact, only caregiver. [He] seeks comfort and reassurance from [her] and seeks her return [when] she leaves his side."

According to Dr Gothard, that will likely have knock-on effects in terms of the amount of specialist therapy he receives.

Down Syndrome Australia said it would be reasonable for Ms Yang's case to get a carer's visa. ( ABC News: Danielle Bonica )

"Early intervention starts with children with Down syndrome basically from day one — physio, speech therapy — Leo has missed out on all of that because he's got leukaemia," Dr Gothard said.

"If he goes into a foster home, he's very unlikely to get the early intervention that he really needs."

And then there is the cost.

"Supporting the mum to stay in Australia would actually be a lower cost to the system than the child ending up in foster care and needing to be in out-of-home care for the rest of his life," Dr Skladzien said.

Another option would be for Leo to apply for Chinese citizenship [he has no automatic right to live in China] and return home with his mum, but no-one involved in his care believes that is a good option.

"There is a lot more stigma associated with intellectual disability and Down syndrome in China," Dr Skladzien said.

"Staying in Australia is definitely going to lead to better outcomes for him."

A Home Affairs spokesperson says the Minister has the power to intervene if he thinks it is in the public interest, but the department does not comment on individual cases.

'I want to see him grow up'

While Ms Yang awaits an outcome, her life is a precarious balance between keeping the anguish of her past at bay, while not being paralysed by her uncertain future.

"[I] live day-by-day and try to enjoy every moment with Leo first," she said.

"I try not to have too many bad thoughts about life or about people because I want Leo to be able to enjoy happy moments with me … if I kept thinking about whether it's fair or whether it's just then I would be drowning in those thoughts non stop."

A child with Down syndrome and leukaemia will need "a lot of care and support," Dr Skladzien said. ( ABC News: Danielle Bonica )

She is often overwhelmed — and in her darkest moments, she says it is her son that supports her.

"He's just my son. He's just my sunshine, so he can help me stay away from the darkness," she said.

"Sometimes if I feel very upset and depressed and maybe bitter, I will try to hold his little hand, or hold his little feet, I will kiss him and cuddle him to try to get comfort and some warmth from him because he's such an angel."

Sometimes she lets herself imagine, for a fleeting moment, what their future together might be like.

"I want to be able to see him grow up and maybe make many friends in his life. I want to maybe cook with him together and maybe go out for a walk," she said.

"I don't want to be too greedy."

*Names have been changed to protect identities