Lab News & Events February 5, 2020

"Nearly one in 25 of the couples we tested now know they have a high chance of having a child with a severe recessive genetic disease."

Professor Nigel Laing AO
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WA’s first pre-pregnancy study finishing screening for more than 200 couples

The first major pre-pregnancy screening study in WA found around 4% of couples were at risk of having a baby with one of the more than 470 severe recessive genetic diseases being screened for.

The study was screening for conditions that cause death or disability before the age of four.

Professor Nigel Laing AO, an internationally acclaimed genetics researcher who heads the Neurogenetic Disease Laboratory at Perth’s Harry Perkins Institute of Medical Research said this was the first time screening for a large number of recessive diseases had been offered to the public in WA and was one of the first major studies in Australia.

“We’ve learnt a lot from running this pilot study. One surprise was the unexpectedly high rate of high risk couples we identified, a result that we are still trying to understand.

“Out of the first 185 couples we screened we identified 8 couples with recessive genetic mutations that could affect their baby.

“That’s nearly one in 25 of the couples we tested who now know they have a high chance of having a child with a severe recessive genetic disease.

“For one of those couples the carrier screening also identified the reason they had previously lost a child,” Professor Laing said.

PhD student Royston Ong, whose research formed the basis for the study, said the results showed couples are very interested in having screening before starting a family.

“The take-up rate we had from couples wanting screening and the discovery that 4% of couples have an increased chance of having a baby with one of the conditions tested for, shows the value of screening,” he said.

Rare diseases and malformations cause 51% of deaths in the first year of life. However, nearly 90 per cent of couples at risk of having babies with devastating genetic conditions have no family history of the disorders and no idea they are potential carriers and at risk of having an affected baby.

The likelihood of a baby being born with just one of three commonly screened conditions, cystic fibrosis, fragile X syndrome or spinal muscular atrophy (SMA) which can cause paralysis and death in babies, is comparable to the chance of having a child born with Down syndrome.

“One in 50 people are carriers for SMA, and if they partner with another carrier they have a one in four chance with every pregnancy of having a baby with SMA,” Professor Laing said.

The pilot project was run by the Harry Perkins Institute of Medical Research in Perth, the WA Department of Health’s Genetic Services WA, PathWest and the Busselton Population Medical Research Institute.

“Our WA carrier screening project was largely funded by a young philanthropic couple who themselves had a child affected by a still unknown disease.

“The support of the Zac Pearson Legacy, a foundation set-up by former Olympic swimmer, Todd Pearson and his wife Alisa to honour their son, Zac, who died at 22 months, enabled the study.

“I would like to thank the Pearson family for generously supporting WA’s first screening program, and thank the couples who volunteered to be screened,” Professor Laing said.

The WA study team is now collating all the information gained from the Busselton study and providing data and lessons learned to the national program, Mackenzie’s Mission, soon to be available for Western Australian couples.

“I hope that in the future as more genetic screening occurs in Australia, there will be a strong focus on identifying carriers before they have affected children and most important of all that we will be diagnosing far fewer children with severe genetic diseases”, Professor Laing said.

Mackenzie’s Mission, named after baby Mackenzie Casella who died at seven months from SMA, is being administered by Australian Genomics and coordinated in WA by Professor Laing’s team at the Harry Perkins institute of Medical Research.

It aims to screen 10,000 couples Australia-wide and will screen for more than 700 genetic conditions. Mackenzie’s Mission is due to commence full recruitment of volunteer couples in WA in February.