Trial for rare 'black bone disease' wins funding

The Alkaptonuria (AKU) Society, a UK charity and patient organisation for the rare disease of the same name, has won a £5 million grant from the European Commission to help finance clinical trials of a treatment for the condition.

The AKU Society's chairman, Nick Sireau, gave up his job three years ago to join the charity. He told BBC Radio 5 Live that when his two sons were diagnosed with the disease, doctors told him that 'there is no treatment and we should basically go home and try not to think about it... but we went home and thought, "we need to do something about this"'.

AKU is a rare genetic condition, discovered in 1902, and currently known to affect only 64 people in the UK. It is inherited in an autosomal recessive pattern and causes a deficiency of the enzyme homogentisic dioxygenase, which in turn leads to build-up of a toxic acid, homogentisic acid (HGA) in the body. It is the build-up of HGA which causes health problems.

One of the first symptoms of AKU is black urine. Rare conditions are often misdiagnosed at first and this was the case for Sireau's sons. He told the BBC that when he first noticed black urine in his son's nappy, the doctor suggested that this was due to his wife eating red cabbage, and passing on the colour via breast milk.

Later, the acid accumulation causes cartilage and other connective tissues to turn black (accounting for AKU's alternative name — 'black bone disease') and can lead to severe early osteoarthritis. Other parts of the body that can be affected include the heart valves, kidneys and prostate.

Nitisinone, the drug to be trialled by the AKU Society, prevents the accumulation of the toxic acid by inhibiting the enzyme which makes it. If given early in life, this could reduce occurrence of the health problems associated with the condition. It could be 'effectively a cure', Sireau told the Mirror.

In 2011 the National Institutes of Health in the USA published a clinical trial of nitisinone in 40 AKU patients over three years, showing that HGA urine levels were reduced by up to 95 percent. However, range of motion at large joints was not significantly different between the treatment and control groups.

Sireau aims for more patients in the new trial, which will have centres in Liverpool in the UK, France and Slovakia, in order to better assess the effectiveness of the drug. The hope is that if the drug is shown to be beneficial, it will be licensed for use in AKU by the European regulator, the European Medicines Agency.