International 4p-/Wolf-Hirschhorn Syndrome Awareness Day Date in the current year: April 16, 2025

Wolf-Hirschhorn syndrome is caused by a deletion within chromosome band 4p16.3 of the short arm of chromosome 4. In approximately 87% of cases, the deletion is de novo, i.e. not inherited from either parent. In the remaining cases, it is inherited from a parent who has a chromosomal translocation (unusual rearrangement of chromosomes). It is a rare condition, occurring in about 1 of 50,000 births; for unknown reasons, it affects females twice as often as males.

The syndrome was first described in 1961 by the Austrian-born American pediatrician Kurt Hirschhorn, but it was the work of the German geneticist Ulrich Wolf that brought it to worldwide attention. To highlight the contributions of Hirschhorn and Wolf, the syndrome was named after both of them.

The most common characteristics of Wolf-Hirschhorn syndrome are typical facial features: smaller-than-normal head (microcephaly), undersized jaw (micrognathia), short medial cleft, prominent glabella (area between the eyebrows and above the nose), abnormally increased distance between the eyes, and ear tags (benign growths in front of the ear). The syndrome also causes growth delay, muscle hypotonia, seizures, congenital heart defects, and intellectual disability.

The severity of symptoms depends on how much genetic material was deleted, which can range from a very small break to about 50% of the short arm. Some children with the syndrome are near normal height and weight and can walk, talk and help with their daily care, while others are very short, severely underweight, and require constant care. An estimated 30% of those affected die within the first few years of life. Treatment focuses on managing symptoms on an individual basis.

International 4p-/Wolf-Hirschhorn Syndrome Awareness Day was jointly established by several national charities that support people Wolf-Hirschhorn syndrome and their families. They include 4p- Support Group (North America), the Spanish Wolf-Hirschhorn Syndrome Association (Asociacion Española del Sindrome Wolf-Hirschhorn), the Italian Wolf-Hirschhorn Syndrome Association (Associazione Italiana sulla Sindrome di Wolf-Hirschhorn), the Australian Wolf-Hirschhorn Syndrome Support Group, and the Wolf-Hirschhorn Syndrome Trust (UK and Ireland). The date of April 16 (4/16) was chosen to represent the 4p16.3 deletion.

You can get involved with International 4p-/Wolf-Hirschhorn Syndrome Awareness Day by learning more about this rare genetic disorder and sharing what you’ve learned with others, wearing jeans with a hole in them to show support and start conversation (the hole symbolizes the missing genetic material in chromosome 4), organizing an awareness event in your community, donating to a charity that supports Wolf-Hirschhorn syndrome patients and their families, and spreading the word on social media.