CEREBRAL palsy remains the commonest physical disability of childhood affecting one in 500 Australian children.
It is a group of permanent disorders that affect the development of movement and posture, causing activity limitations attributed to non-progressive disturbances occurring in the developing fetal or infant brain.
The motor disorders of cerebral palsy are often accompanied by disturbances of sensation, perception, cognition, communication and behaviour, and by epilepsy and secondary musculoskeletal problems. It is a heterogeneous condition with many different aetiologies and with risk factors occurring in preconceptional, antenatal and postnatal epochs.
For many years, the accepted dogma relating to the aetiology of cerebral palsy — the result of opinion rather than evidence — focused all attention on labour and birth.
For many years, research into the causes of cerebral palsy sat in the too hard basket, leading to ever greater interventions in birthing with minimal impact on the incidence of the condition.
More recently, the dogma has been questioned and a more scientific approach brought to bear. This has led to a significant increase in research in the areas of aetiology, early detection, prevention and evidence-based interventions in cerebral palsy.
We have suspected for a while that much of the aetiology of cerebral palsy is genetic in origin, with genetic links also shown in autism, epilepsy and intellectual disability.
Thanks to the cerebral palsy registers, the first of which was established by Professor Fiona Stanley in the 1970s in WA, a whole population-based approach became possible rather than anecdotal case series.
This register was joined by registers based in other states and territories, culminating in the Australian Cerebral Palsy Register. Data from these registers and from a large case control study linked with the birth defect registers demonstrated that over 30% of people with cerebral palsy born at term had a birth defect, which was usually not cerebral in origin. Moreover, male sex is known to be a risk factor for cerebral palsy (as it is for many other neurodevelopmental conditions). A family history of cerebral palsy is found in 1% of people with cerebral palsy and consanguinity is a risk factor.
A recent preliminary study from Australia used whole exome sequencing to examine 183 children with cerebral palsy where one or both parents were available. Among 98 cases where sequencing was available and both parents, researchers found variants that were putatively disease causing in five known disease genes and eight novel candidate genes.
Though they have not demonstrated causation, the plausibility of these findings and the identified crossover with genes playing a role in intellectual disability, strongly suggest a significant genetic contribution in many cases of cerebral palsy.
This is a beginning and much more needs to be done. We are sure that only the tip of the iceberg has as yet been uncovered.
Research is expensive and time consuming, with international collaborations that are underway often, as in the Australian study, and with significant funding from philanthropic trusts. Yet, it is very encouraging to see a wider net being cast in understanding the aetiology of this burdensome condition.
Most parents with a child with cerebral palsy are driven to know why this has happened and this latest study opens a doorway to a possible explanation for some.
It is our hope that researchers will go through this open door in a cooperative and collaborative effort to shine a light on aetiological pathways that may be amenable to prevention and possibly a cure, both for those who are already affected and those that need not be in the future.
Professor Nadia Badawi is the Macquarie Group Foundation professor and chair of cerebral palsy at the University of Sydney. Dr John Keogh is a Sydney obstetrician and gynaecologist with a special interest in research into the causes and outcomes of babies born with neurological problems in the first week of life.