International 4p-/Wolf-Hirschhorn Syndrome Awareness Day is observed worldwide every April 16 to highlight the genetic condition caused by a partial deletion of chromosome 4, which leads to distinctive facial features and intellectual disability. The syndrome, first described in 1961 by pediatrician Kurt Hirschhorn and brought to attention by geneticist Ulrich Wolf, affects approximately 1 in 50,000 births and is more common in females. Common characteristics include microcephaly, micrognathia, and growth delays, with treatment focusing on managing individual symptoms. The day was established by several national charities, including the 4p- Support Group (North America) and the Wolf-Hirschhorn Syndrome Trust (UK and Ireland), with the date symbolizing the 4p16.3 deletion. People participate by learning about the disorder, wearing jeans with holes to represent the missing genetic material, organizing community events, and donating to relevant charities.