Maartje is a clinical geneticist at the LUMC’s Department of Clinical Genetics, with a track record on clinical research in hereditary cancer risk and polyposis. Since receiving a personal grant from the Dutch Cancer Society in 2012, she has secured further funding, enabling her to combine clinical practice with research. Her contributions have been recognized through severeal awards, including the Marie Parijs Prize and the Janssen Gastrointestinal Research Prize. Maartje’s research primarily focuses on analyzing cancer risk in genetically predisposed families and establishing large clinical databases of patients with mutations in genes such as MUTYH, PMS2, and MSH6.
More recently, she has -in cooperation with the pathology department- investigated unexplained colonic polyposis (CPUE) in over 500 patients to identify mosaic mutations in the APC gene.
The detection of mosaic pathogenic variants is challenging because in contrast to inherited variants, since somatic variants only exist in small and variable proportions of cells, ranging from embryonic mutations present in most cells to mutations present only a subset of the cells. By applying sensitive next-generation sequencing in tumor DNA isolated form adenomas, mosaicism was identified in approximately 10% of tested unexplained polyposis cases. Some patients show hybrid mosaicism, where multiple but not all lesions share the same APC variant, and this was often linked to colibactin-associated mutation signatures, highlighting an important environmental factor in adenoma formation.
Ongoing efforts are being done to define their clinical features and develop screening recommendations for this group.
