17q21.31 microdeletion / KANSL1 mutations: Koolen-de Vries syndrome
Summary Koolen syndrome or Koolen-de Vries syndrome is characterized by moderate to severe intellectual disability, hypotonia, amiable behavior, and highly distinctive facial features. Koolen syndrome is most frequently a chromosomal disorder (when caused by microdeletion 17q21.31, also called monosomy 17q21.31), but can also arise as a monogenic disorder (when caused by a point mutation in the KANSL1 gene). Detailed