New Light Shed On Serious Abnormalities In Babies

New Light Shed On Serious Abnormalities In Babies

Every year in NZ, at least 15 babies are born with a serious and life threatening congenital abnormality called oesophageal atresia. Babies with this condition have part of their gullet (oesophagus) missing, and the lower end of the gullet has an abnormal connection or hole between it and the trachea (windpipe). Without surgery these babies die, as milk cannot be swallowed and ends up in the lungs, causing pneumonia.

What normally happens with oesophageal atresia is that the child undergoes surgery one or two days after birth, with the vast majority surviving, although some have ongoing problems with swallowing that persist well into childhood.

The cause of this serious abnormality has so far been a mystery. Now a paediatric surgery researcher at the Christchurch School of Medicine and Health Sciences, Dr Dejan Arsic has shed new light on how this, and other related abnormalities, might come about.

As part of his PhD research Dr Arsic has honed in on a specific protein called Sonic hedgehog (Shh). This acts as a signalling molecule, and is vital for the development of parts of the body like the oesophagus and trachea.

“We haven’t discovered this molecule as such, but what we have found out which has not been understood before is that the actual levels of this protein in the tissues have a major impact on the development of this type of abnormality, and maybe others too,” he says.

Dr Arsic’s original findings have shown for the first time that the Shh protein is a vital message carrier for the formation of the foregut, including the trachea and the oesophagus. When this is being developed, the fetus has high levels of this protein in the region where these organs are developing. If the levels of Shh are low there is a risk of the oesophagus not developing normally, one part of it joining the windpipe and developing a hole between the two vital tubes which carry air and food to the body.

Dr Arsic has also shown that as the fetus approaches birth, the level of Shh declines naturally, but in those children born with these and other malformations, the protein levels stay low throughout gestation period.

The next step in unravelling this condition is to identify genes involved in the development of the gastrointestinal tract. Then it may be possible to prevent these abnormalities from occurring, or at least diagnose the condition before birth.

Dr Arsic’s research has recently been published in the prestigious specialist journal Pediatric Surgery International. He has also won two prizes from the Australasian Association of Paediatric Surgeons for his research.

This research has been supported by the University of Otago’s PhD Scholarship and the Canterbury Medical Research Foundation.

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