A five-year-old boy born in Australia is facing deportation to Bangladesh with his family after their visa applications were refused because his “mild disability” would be a burden on the medical system.

Dr Mahedi Hasan Bhuiyan arrived in Australia on a student visa in 2011. He and Rebaka Sultana married the next year in Bangladesh and she joined him in Australia in 2013. Later that year their son, Adyan, was born at a Geelong hospital.

A few months after his birth, Bhuiyan and Sultana noticed Adyan was struggling to lift up his head. Tests revealed he had a mild cerebral palsy, likely caused by a stroke shortly before or after his birth.

Bhuiyan, who has a Bangladeshi degree and a South Korean masters, finished his PhD in engineering at Deakin University in 2016. He was granted a Victorian state government nomination for a permanent skilled migration visa, which would allow his family to build a life in Australia.

However, because of Adyan’s disability, it was rejected under Australia’s strict “one fails all fail” visa health criteria.

Bhuiyan’s family appealed the rejection through the administrative appeals tribunal.

Two-and-a-half years later, the AAT upheld the refusal, noting it was “bound to accept” the findings of Adyan’s medical assessments in 2016 and 2019.

The 2019 medical assessment found Adyan had a “mild functional impairment” which was likely permanent, and would likely require community services “including but not limited to additional support at school”.

“I do not have any idea why a kid having little weakness in his left hand will need special education,” Bhuiyan said. “As far as I can understand, special education is required for those who are unable to attend in the mainstream schools.”

A separate medical assessment seen by Guardian Australia says Adyan is independently mobile and only requires a support rail to navigate steps and uneven surfaces. It notes he is very vocal, enjoys playing with a soccer ball and has developed movements to adapt around his disabilities.

Dr Mahedi Hasan Bhuiyan, Rebaka Sultana and their son Adyan.

It does not assess cognitive function, which the report recommended prior to starting school, and does recommend continued therapy support in Australia or Bangladesh.

Bhuiyan said Adyan goes to kindy every day and that the parents help him with physical therapy.

“He’s very good now, very good,” he said. “No learning difficulties, he’s going to school and learning everything and watching kids videos at home.

“Now he can grab things, when before he couldn’t grab anything.”

In its ruling, the AAT said it had no discretion to take into account the contributions the family had made to Australia.

The family has appealed to the immigration minister, David Coleman, as their last chance at staying in Australia. The minister’s discretionary powers allow him to grant or deny a visa. He is not compelled to make a decision, or explain it.

Bhuiyan is on a bridging visa E, a restricted three-month visa that allows the family to legally live in Australia while they wait for the outcome of their appeal to the minister.

He works a casual job while Sultana keeps studying for the exam to have her qualifications as a doctor recognised in Australia.

“Every three months my visa is extended,” Bhuiyan said. “This situation is very difficult for me. My Deakin university supervisor told me he would include me on a project as soon as my visa situation is resolved.”

Bhuiyan said he was not worried about his future in either country but wants to stay in Australia and have his son educated here.

The minister has previously granted visas to families in similar situations, including a Bhutanese family who lived in and worked in Australia for seven years who were facing deportation because their deaf son would be a “cost” to the taxpayer.

The minister also granted a visa for a Filipina nurse working in Townsville, and her 10-year-old son whose visas were rejected because of his autism diagnosis. They arrived in Australia when he was two and he was diagnosed shortly after.

In 2017, Bangladeshi doctor Nasrin Haque was given a last-minute reprieve after she was rejected for permanent settlement after eight years living and working as a GP in Australia, because of her daughter’s autism. Her sister, brother and parents are all Australian citizens.

The home affairs department does not comment on individual cases but has previously noted the ministerial intervention appeal is not an extension of the visa process, and all cases are decided on their merits.