Every baby in Australia and New Zealand is offered newborn screening. The test is done within the first 24-72 hours after birth and is used to detect several conditions including phenylketonuria (PKU), hypothyroidism, cystic fibrosis (CF) and congenital adrenal hyperplasia (CAH). Clinical scientist, Mark de Hora explains how learnings from New Zealand’s screening program are being applied to the screening process in Australia.

“We screen to save babies lives. The idea is that we can detect disease before the parent notices any symptoms, we can start treatment earlier and the baby develops normally. One of the conditions we screen for is congenital adrenal hyperplasia (CAH) which occurs when a baby has a gene mutation that causes a specific enzyme deficiency in the adrenal glands. They are not able to produce enough cortisol and aldosterone and in the severest mutations, unless it is detected in the first week after birth, the baby will develop life-threatening dehydration, shock and electrolyte abnormalities.

“Babies can survive for a few weeks with their mother’s circulating hormones but are unable to produce their own when needed. However, once the disorder is detected, the baby can be given the hormones they need. This treatment needs to be given quickly and will need to be managed through childhood,” said Mr de Hora.

New Zealand has been screening for congenital adrenal hyperplasia since 1984. Around 2-3 babies are detected each year and the incidence is around 1 in 15,000. Screening for the condition in Australia only began in 2018 and it has been rolling out nationally over the last couple of years. Because Australians are introducing a similar technology to that used in New Zealand, Mr de Hora and his team are working with their Australian colleagues to help implement it.

“One of the biggest problems with screening is false positive results. This can cause a lot of unnecessary anxiety in families and can be expensive because babies have to be retested and often undergo further diagnostic evaluation. This is something that we have been working to eliminate in New Zealand and we have now introduced a new test which is commonly used in chemical pathology laboratories across the country. When we looked at how our screening performed over a 4-year period, it showed that we have managed to eliminate almost all false positives, which is fantastic.

“Recently, several countries, including New Zealand have published the improvements they have made to their newborn screening programmes for CAH. This will help other countries, such as Australia, to improve their screening and ensure their results are as accurate as possible. This sharing of data between countries is essential. In New Zealand we get around 60,000 births per year but if you look at the whole of Australasia, there are around 400,000 births per year. If we can collaborate and consider our combined experience of rare diseases, this is much better as we can learn faster and benefit from each other’s experience,” said Mr de Hora.