Researchers at Sydney Children’s Hospital, Randwick (SCH) have found a new cost-effective testing method to support family planning for those living with rare genetic disease, Tuberous Sclerosis Complex (TSC).

TSC is an incurable multi-system genetic condition caused by genetic changes found on either the TSC1 or TSC2 genes. The condition causes non-cancerous tumours to grow in parts of the body including vital organs like the brain, heart or lungs.

Study lead and Clinical Geneticist at SCH, Dr Clara Chung, said the severity of the condition is impossible to predict, which is why testing is so important.

“Some cases are so serious they require surgery and lifelong tumour monitoring, while others are so mild that a person may not even know they have it,” Dr Chung said.

“A genetic diagnosis is especially crucial for those planning to have children, because the chance of a parent with TSC passing the unpredictable condition to their child is 50% or 1 in 2.”

TSC often cannot be diagnosed using standard genetic testing due to the mutations being so small and scattered. Deep genomic sequencing does provide a reliable alternative however, this testing is labour-intensive and costly, which limits its use in routine hospital settings. 

In an effort to find a more efficient diagnosis method, Dr Chung trialled a new partial deep genomic sequencing method that halved testing time and significantly reduced associated costs.

“What we essentially trialled was a method, that reads the genome 500 times instead of 1,000. Also, instead of testing just a patient’s blood, we tested a mouth swab and skin sample as well,” Dr Chung explained.

“What we found was this method identified the TSC-causing gene variants without needing to read as many times, making it very cost-effective.”

The success of the trial has since seen a similar testing method implemented at the Randwick precinct and approved by the National Association of Testing Authorities (NATA).

“For those living with TSC, the outcomes of this study are hugely beneficial. It will give them the information they need to assist with family planning so they can make the decision that’s right for them,” Dr Chung said.

Dr Chung's research has been published in the journal of Molecular Genetics and Genomic Medicine.

Dr Chung works within the Centre for Clinical Genetics, a clinical service with integrated research activity based at SCH part of Kids Research. She is also a conjoint lecturer at the UNSW Sydney.