People with beta-thalassaemia can have lifelong anaemia, needing regular blood transfusions; people with sickle cell disease, whose red blood cells are abnormally shaped, typically like a sickle, can suffer from blood vessel blockage, causing episodes of severe pain called sickle cell crises, anaemia and complications affecting major organs, which can occasionally be fatal. These blood disorders affect more than 20 million people worldwide: five per cent of the world’s population carry the trait genes for haemoglobin disorders and 300,000 babies are born each year with severe sickle cell disease.

Patients with beta-thalassaemia and sickle cell disease who produce higher levels of foetal haemoglobin have milder forms of the diseases when compared to patients who produce less foetal haemoglobin—something that had been known for many years, says Thein. But what remained unclear was why the former would occur.

Thein saw the potential to treat the disease by manipulating the levels of foetal haemoglobin in patients.

In 1982, she joined the Weatherall Institute of Molecular Medicine (WIMM) at the University of Oxford as a junior clinical fellow, where she studied under famed haematologist Sir David Weatherall. She began identifying patients with milder forms of betathalassaemia and collecting blood samples from these patients and their family members, with the goal of identifying the genes associated with different severities of these blood diseases.

It took her and her team two decades before a breakthrough, when they identified the gene BCL11A, a major suppressor of foetal haemoglobin production.

The late 2000s saw the invention of the world’s first genome editing technology Crispr, which enabled other scientists to edit this particular gene in the extracted stem cells of patients, which would counteract the effects of beta-thalassaemia and sickle cell disorders.

The therapy is not easily accessible. Fast-forward to May 2024, when Kendric Cromer, a 12-year-old boy, became the first person with sickle cell disease in the world to receive this months-long treatment process, at Children’s National Hospital in Washington DC. It costs US$3.1 million (about HK$24 million), making it one of the most expensive medical treatments of all time. Bluebird, the commercial company that runs the therapy, only offers it to between 85 to 105 patients every year. “Not many hospitals have the resources or the sophisticated kind of labs to be able to do this stem cell processing,” Thein says.

She is now developing drugs for sickle cell anaemia that can be “more accessible to people from all over the world and all walks of life, in poor and middle-income countries”. The oral tablet, to be taken daily, helps slow down the sickling process, reduce destruction of red blood cells and alleviate some symptoms of sickle cell anaemia. “The patient can live with the disease and not have to undergo gene therapy.” At the time of writing in December, the drug was undergoing clinical trials in almost 100 centres around the world. If it passes, Thein expects that it’ll be available in two to three years’ time.

Thein’s research continues. “I’m always excited to explore new drugs and alternative ways for treating sickle cell patients,” she says. Already, she has the idea of developing tools that can help predict the severity of the illness in a patient with sickle cell disease, which can help doctors determine the most suitable treatments at an early stage.

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Looking back, she attributes the remarkable discoveries she has made in her career and her persistence, which she deems a crucial characteristic for a researcher, to her mother. Born in Kuantan, a small town in Malaya (now Malaysia), Thein came from a modest family who couldn’t afford to send her to university. “My mother single-handedly brought up nine children [including Thein herself ]. Although she didn’t finish school, she greatly valued education,” Thein says. “Because of her, I’ve always believed in working hard.”

At school, Thein enjoyed biology and biochemistry. She went on to earn a scholarship to study medicine at the University of Malaya in Kuala Lumpur. “I was the only member of my family to get a college degree.”

Seeing the lack of cutting-edge medical technology and infrastructure in Malaysia in the 1970s, she moved to the UK to further her studies and, in time, took up positions including senior scientist at WIMM and professor of molecular haematology at King’s College London, where she was also a physician and clinical director of the Red Cell Centre in King’s College Hospital. In 2015, she moved to Washington DC to join the National Institutes of Health, which had just opened a branch that specialised in sickle cell studies.

With her achievements every step of the way, she has made her family and country proud. “I’m pleased to represent my ethnicity and gender, but there should be more of us,” she says. “Historically, women have had to work harder in their educational and career path. We’re [deemed the] central caregivers at home; we have to juggle to succeed; we are masters at multitasking. I am flexible with my staff ’s working hours, in particular women, because I know they make up for the time when they’re not at work in person.”

Thein hopes that her work will not only mean a chance for human advancement in healthcare but also set an example that women can be a leading force in the industry. “I don’t want to be appointed [to higher roles] for being a woman. I want to be appointed based on my skills and ability. Equally, I do not want to offer a position to fill a minority or gender quota,” she says.

“I would like us to reach a state where diversity is the norm. There’s no need to say, ‘Wow, there are females among so many male [scientists].’ We should continue to support more women and other [minority] groups to become the norm rather than an exception.”

Front & Female Changemakers celebrates the extraordinary journeys of inspiring women who have emerged as powerful changemakers in a range of fields, offering a glimpse into their lives and showcasing their courage, vision and relentless pursuit of change and progress. From social entrepreneurs and business leaders to educators, artists, activists and scientists, Front & Female changemakers exemplify the ability to challenge the status quo and demonstrate the power of women to effect change.

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