Professor Raymond Liang Hin-suen, chairman of the government’s Steering Committee on Genomic Medicine, said the project could potentially identify more genetic factors behind diseases that are yet to be diagnosed or cancers that could be hereditary.

“If we can identify those [disease-causing] genes, hopefully we can stop them being passed on to the next generation,” said Liang in an interview last week .

Currently, thalassaemia, some forms of breast cancer, colorectal cancer and muscular dystrophy, are among a few dozen serious genetic diseases that can be identified and prevented in a test during in vitro fertilisation (IVF) treatment.

The test, known as pre-implantation genetic diagnosis, looks into a specific genetic diseases among embryos during an IVF treatment. Only the one without the disease-related gene would be transferred into the mother’s womb.

It would prevent people who have a family history of a genetic disease or who are carriers of a genetic condition from passing the illness to the next generation.

“Hopefully, through this project, we can raise the chance of identifying [more diseases],” Liang said.

Amid an ageing population, the city’s fertility rate has been gradually declining, from 1,196 per 1,000 women in 2015 to 1,052 last year. More women hoping to have babies in Hong Kong have in recent years turned to IVF, a set of procedures that enables a combination of an egg and sperm outside the body.

Ernest Ng Hung-yu, a clinical professor who works on reproductive medicine in the University of Hong Kong, said the amount of tests for genetic diseases performed during IVF treatment had also increased steadily in the past few years at Queen Mary Hospital, from 60 in 2017 to 80 last year.

While Ng agreed that digging out genomic information of unknown disorders could help prevent more of those diseases before birth, he said the impact might not be felt soon.

“It is a complicated matter. Even if you have identified a certain gene, it would take further time to check whether it is key [in causing a disease]. This is not a short process,” Ng said.

Genetic data gathered in the project, for which HK$1.2 billion (US$155 million) has been earmarked and patient recruitment could start in the middle of next year, would also bring a wider benefit for research and development as the government aimed to establish a database specifically for the local Chinese population.

This could shed light not only on uncommon disorders and cancers, but also on more prevalent diseases affected by genes, such as diabetes and dementia, Liang said.

Currently, around 70 per cent of data in the human genome reference database commonly used by researchers internationally were from Caucasians, according to Deputy Secretary for Health Fong Ngai.

“Applying these data on the Chinese population might not be accurate,” he said.

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He said the experience in Britain showed that the diagnostic rate for uncommon disorders has increased from 10 per cent to up to 40 per cent after similar genome studies were done, expressing hope that the city could also see such improvement.

Dr Luk Ho-ming, a specialist in genetics and genomics from the Department of Health, said there could be problems in applying data of other races to Chinese people.

He used breast cancer for an example, saying that a certain genetic mutation indicating the disease for Westerners did not mean the same for Chinese people.

While a genetic database specifically for the local population would be established, Fong said there would be an interface combining clinical information from the big data platform of the public hospitals.

“It is not enough just to have genomic data. It would only be meaningful when they are studied together with clinical information,” he said. “Only in this way can the research be facilitated.”