Siân is a Consultant Nephrologist in Cardiff with a sub-specialty interest in immune mediated kidney disease, including glomerulonephritis and transplantation. She qualified from Cambridge University and undertook clinical training in London, East Anglia, and Melbourne. She completed a PhD in immunology at the University of Cambridge and a post-doctoral fellowship at the University of Washington, Seattle.

Her research focuses on improving the management and patient impact of immunologically mediated kidney disease, including personalised management of immunosuppression, patients with failing kidney transplants, clinical trials and holistic care including reproductive goals for patients with kidney disease. She is deputy director of the Wales Kidney Research Unit (http://www.kidneyresearchunit.wales) and unit lead for late phase trials, and an executive board member of the UK Organ Donation and Transplant Research Network (https://www.ukodtrn.org).