As a Pediatrician, Holm has developed a strong interest in supporting patients with genetic PTEN defects. As a research focus, he investigates rare genetic disorders that can lead to intestinal inflammation. Together with an international team of investigators, Holm has established that patients with PTEN harmatoma tumor syndrome (PHTS) develop autoimmunity and immune dysfunction. Understanding of the immune pathways that are dysregulated in patients with genetic defects in PTEN might not only allow to correct the immune dysfunction in PHTS itself but also help to understand general mechanisms that contribute to autoimmunity and intestinal inflammation.