Qld baby with rare genetic disorder trials experimental drug

A baby with an extremely rare genetic disorder is trialling an experimental drug, thanks to an early diagnosis by a Queensland Children’s Hospital doctor.

SIXTEEN-month-old Mason Hamilton has a genetic condition so extremely rare, he’s one of only a handful of known cases in Australia, but his doctor suspects others remain undiagnosed.

Mason is the youngest Australian diagnosed with Allan-Herndon Dudley syndrome, which causes intellectual and physical disability.

Some families wait years for an answer to a child’s disability, but Mason’s early diagnosis at five months old, thanks to the expertise of Queensland Children’s Hospital endocrinologist Tony Huynh and Mater Pathology staff, has allowed him to start treatment with an experimental drug, Triac.

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Kate Hamilton with son Mason, 16 months, who has been diagnosed with a rare disorder. Photo: Peter Wallis

Although Dr Huynh is cautious about the benefits of the drug before more research is done, Mason’s Mum Kate believes her son is improving on the medication and with regular physiotherapy and occupational therapy.

His head control is better, he’s aware of his surroundings and for the first time, he’s looking into his mother’s eyes.

“He’s very developmentally delayed, there’s no questioning that,” Mrs Hamilton said. “But we see him progressing. It’s very, very slow and he’s never going to be at his peers’ level. But he is making gains. The drug has made a big difference. It’s sort of woken him up.

“We just want to ensure that he gets the best chances possible and get him to be the best that he’ll be able to be.”

Mason, who has a four-year-old sister Alexandra, was born with a mutation in the SLC16A2 gene, which causes a deficiency in a transporter protein that carries a crucial thyroid hormone into the brain.

Mason Hamilton, 16 months, with his four-year-old sister, Alexandra. Photo: Peter Wallis

Dr Huynh, who divides his time between the Queensland Children’s Hospital and Mater Pathology, said the thyroid hormone was particularly important in the first three years of life for the brain to develop normally.

Triac, which is being trialled by researchers in Rotterdam, in the Netherlands, is similar to thyroid hormone but doesn’t need the transporter protein to get into the brain.

Diagnosis of Allan-Herndon Dudley syndrome in Australia is difficult because of a lack of awareness about the condition and because Medicare does not fund the necessary thyroid function tests for developmental delay or intellectual impairment.

“It should be paid by Medicare,” Dr Huynh said. “Some studies estimate that Allan-Herndon Dudley syndrome causes up to 1.4 per cent intellectual impairment in boys.”

He praised Mrs Hamilton’s advocacy for Mason and for raising awareness about Allan-Herndon Dudley Syndrome, which has a suspected incidence of less than one in a million. Only boys are affected.

“She truly is a warrior for her child,” Dr Huynh said. “She’s articulate, she’s determined. She has basically been on the front foot to do everything possible for him.

“She’s a role model for a lot of parents with devastating conditions like this, currently with no definitive answer and a lack of resources to help.”

Today is Rare Disease Day.

For more information rarediseaseday.org

To follow Mason’s progress on Facebook or Instagram: mase.mans.mum