Ava’s doctors hadn’t heard of maple syrup urine disease – but a new helpline for rare conditions could help those like her

Ava Rees has a rare metabolic disorder called maple syrup urine disease, which is estimated to affect one in 250,000 people. Photograph: Tammie Rees

When Tammie Rees tells people her daughter Ava has maple syrup urine disease, most people, not even medical professionals, have heard of it before.

The rare metabolic disorder is caused by a defect in the enzymes that break down amino acids which come from protein. Without treatment, the urine smells very sweet, like maple syrup. If the harmful build-up of the amino acids build up in the blood, it can cause brain damage.