David A. Koolen

David A. Koolen is a Dutch clinical geneticist in the Department of Human Genetics at Radboud University Medical Centre in Nijmegen. He took his medical degree at Radboud University Nijmegen in 2002, trained in human genetics there from 2003 to 2011 and earned his doctorate cum laude in 2008 with a thesis on copy number variation and mental retardation. In 2006 he and colleagues reported a new microdeletion at chromosome 17q21.31, tied to a common inversion polymorphism and recognised in people with intellectual disability, low muscle tone and a characteristic face. Six years later a team including him showed that mutations in the gene KANSL1 cause the same picture. The condition now carries his name beside that of Bert de Vries as Koolen-de Vries syndrome, and he keeps collecting clinical data from affected people to build management protocols for it.