Koolen de-Vries Syndrome (KdVS) is a rare genetic disorder with an autosomal dominant inheritance pattern caused by a 500- to 650-kilobase (kb) deletion at chromosome 17q21.31, including KANSL1 or a pathogenetic variant in KANSL1 [1-3]. This evidence concerns the gene KANSL1 and Koolen-de Vries syndrome.