Koolen–De Vries Syndrome Awareness Day, also known as KdVS Awareness Day, is observed worldwide every July 17. This day aims to promote understanding of Koolen–De Vries syndrome (KdVS), a rare genetic disorder caused by a microdeletion or mutation on chromosome 17, particularly affecting the KANSL1 gene. Symptoms can include low birth weight, hypotonia, developmental delays, and seizures, among others. Due to its rarity and the complexity of its symptoms, KdVS is often underdiagnosed, highlighting the importance of genetic testing for accurate diagnosis. The day encourages public engagement through education about the syndrome and support for those affected, including donations to organizations like the KdVS Foundation. Individuals can participate by sharing information on social media using hashtags such as #KdVS and #KdVSAwareness.