WA expert helps lead world diagnosis of rare disorder in newborn babies

A Western Australian-based expert in neuromuscular diseases has helped revolutionise the way doctors around the world diagnose muscle dysfunction in newborn babies.

Professor Nigel Laing, who heads the Neuromuscular Diseases Laboratory at the Western Australian Institute for Medical Research (WAIMR), was contacted by English scientists who diagnosed a baby boy in Oxford with a very rare disorder that caused his muscles to contract strongly in spasms but not relax. A London laboratory analysed the baby’s DNA and found a mutation in the actin gene - which was discovered by Professor Laing’s laboratory in 1999 - to be associated with muscle diseases in newborn children.

Since Professor Laing’s discovery, worldwide identification of mutations in actin has been shown to cause muscle weakness, sometimes called floppy baby syndrome. However, muscle biopsy of the Oxford baby showed the muscle disease nemaline myopathy, which is normally associated with muscle weakness - not muscle hyperactivity. The Oxford case turned that definition on its head and Professor Laing’s team of medical researchers set to work in their Perth laboratory.

“This rare mutation of the actin gene in the Oxford patient had the opposite effect to weakness, even though it was still nemaline myopathy,” Professor Laing said. “It hypersensitised the muscle to calcium (calcium makes muscles contract) so when this patient’s muscles contracted, they hypercontracted in a spasm and wouldn’t relax - they were too active.”

Professor Laing, who is also the Head of Neuromuscular Diseases at the University of Western Australia’s Centre for Medical Research, said the step forward in scientific understanding had changed the definition and perception of nemaline myopathy.

“We know of nearly 200 mutations in actin and this is the first one like this, so it’s revolutionary,” he said.

Professor Laing said the discovery had also changed the view of the world for clinicians who previously would not have thought about this type of genetic defect when diagnosing newborn babies with muscle hyperactivity.

“It warns clinicians across the world that if you see this type of hypercontraction, it can be congenital myopathy. Hopefully this discovery will also lead in future to a therapy for this condition,” he said. “It’s usually easier to stop something working too well - in this case muscles contracting too strongly - rather than not well enough.”

A paper on the finding has been published in Neurology, the journal of the American Academy of Neurology.