Henk-Jan van Slooten studied Medicine in Leiden and earned his PhD there researching the role of cell death regulation in chemotherapy resistance in breast cancer. Part of his PhD research was conducted at the Geraldine Brush Cancer Research Institute in San Francisco.
He did his pathologist training in Amsterdam (AMC, OLVG). He then worked in Alkmaar (Noordwest Ziekenhuisgroep, Symbiant) for over thirteen years, the last six months of which as a Symbiant board member. As trainer in Alkmaar, he was a member of the Central Training Committee and co-founder of the Breast Clinic. In 2018 he made the switch to Pathology-DNA, working at the Nieuwegein location.

Since 2013 Henk-Jan has been a board member of the Palga foundation and shares responsibility there for the development of a protocol reporting module. He is a co-organiser of various symposiums on molecular diagnostics.