Reviewed: January 2009
Published: March 19, 2012
What is Wolf-Hirschhorn syndrome?
Wolf-Hirschhorn syndrome is a condition that affects many parts of the body. The major features of this disorder include a characteristic facial appearance, delayed growth and development, intellectual disability, and seizures.
Almost everyone with this disorder has distinctive facial features, including a broad, flat nasal bridge and a high forehead. This combination is described as a “Greek warrior helmet” appearance. The eyes are widely spaced and may be protruding. Other characteristic facial features include a shortened distance between the nose and upper lip (a short philtrum), a downturned mouth, a small chin (micrognathia), and poorly formed ears with small holes (pits) or flaps of skin (tags). Additionally, affected individuals may have asymmetrical facial features and an unusually small head (microcephaly).
People with Wolf-Hirschhorn syndrome experience delayed growth and development. Slow growth begins before birth, and affected infants tend to have problems feeding and gaining weight (failure to thrive). They also have weak muscle tone (hypotonia) and underdeveloped muscles. Motor skills, such as sitting, standing, and walking, are significantly delayed. Most children and adults with this disorder also have short stature.
Intellectual disability ranges from mild to severe in people with Wolf-Hirschhorn syndrome. Compared to people with other forms of intellectual disability, their socialization skills are strong, while verbal communication and language skills tend to be weaker. Most affected children also have seizures, which may be resistant to treatment. Seizures tend to disappear with age.
Additional features of Wolf-Hirschhorn syndrome include skin changes such as mottled or dry skin, skeletal abnormalities such as abnormal curvature of the spine (scoliosis and kyphosis), dental problems including missing teeth, and an opening in the roof of the mouth (cleft palate) and/or in the lip (cleft lip). Wolf-Hirschhorn syndrome can also cause abnormalities of the eyes, heart, genitourinary tract, and brain.
A condition called Pitt-Rogers-Danks syndrome has features that overlap with those of Wolf-Hirschhorn syndrome. Researchers now recognize that these two conditions are actually part of a single syndrome with variable signs and symptoms.
How common is Wolf-Hirschhorn syndrome?
The prevalence of Wolf-Hirschhorn syndrome is estimated to be 1 in 50,000 births. However, this may be an underestimate because it is likely that some affected individuals are never diagnosed.
For unknown reasons, Wolf-Hirschhorn syndrome occurs in about twice as many females as males.
What are the genetic changes related to Wolf-Hirschhorn syndrome?
Wolf-Hirschhorn syndrome is caused by a deletion of genetic material near the end of the short (p) arm of chromosome 4. This chromosomal change is sometimes written as 4p-. The size of the deletion varies among affected individuals; studies suggest that larger deletions tend to result in more severe intellectual disability and physical abnormalities than smaller deletions.
The signs and symptoms of Wolf-Hirschhorn are related to the loss of multiple genes on the short arm of chromosome 4. WHSC1, LETM1, and MSX1 are the genes that are deleted in people with the typical signs and symptoms of this disorder. These genes play significant roles in early development, although many of their specific functions are unknown. Researchers believe that loss of the WHSC1 gene is associated with many of the characteristic features of Wolf-Hirschhorn syndrome, including the distinctive facial appearance and developmental delay. Deletion of the LETM1 gene appears to be associated with seizures or other abnormal electrical activity in the brain. A loss of the MSX1 gene may be responsible for the dental abnormalities and cleft lip and/or palate that are often seen with this condition.
Scientists are working to identify additional genes at the end of the short arm of chromosome 4 that contribute to the characteristic features of Wolf-Hirschhorn syndrome.
Can Wolf-Hirschhorn syndrome be inherited?
Between 85 percent and 90 percent of all cases of Wolf-Hirschhorn syndrome are not inherited. They result from a chromosomal deletion that occurs as a random (de novo) event during the formation of reproductive cells (eggs or sperm) or in early embryonic development. More complex chromosomal rearrangements can also occur as de novo events, which may help explain the variability in the condition’s signs and symptoms. De novo chromosomal changes occur in people with no history of the disorder in their family.
A small percentage of all people with Wolf-Hirschhorn syndrome have the disorder as a result of an unusual chromosomal abnormality such as a ring chromosome 4. Ring chromosomes occur when a chromosome breaks in two places and the ends of the chromosome arms fuse together to form a circular structure. In the process, genes near the ends of the chromosome are lost.
In the remaining cases of Wolf-Hirschhorn syndrome, an affected individual inherits a copy of chromosome 4 with a deleted segment. In these cases, one of the parents carries a chromosomal rearrangement between chromosome 4 and another chromosome. This rearrangement is called a balanced translocation. No genetic material is gained or lost in a balanced translocation, so these chromosomal changes usually do not cause any health problems. However, translocations can become unbalanced as they are passed to the next generation. Some people with Wolf-Hirschhorn syndrome inherit an unbalanced translocation that deletes genes near the end of the short arm of chromosome 4. A loss of these genes results in the intellectual disability, slow growth, and other health problems characteristic of this disorder.
Where can I find information about diagnosis or management of Wolf-Hirschhorn syndrome?
These resources address the diagnosis or management of Wolf-Hirschhorn syndrome and may include treatment providers.
- Gene Review: Wolf-Hirschhorn Syndrome
- Gene Tests: Wolf-Hirschhorn Syndrome
- MedlinePlus Encyclopedia: Epilepsy
To locate a healthcare provider, see How can I find a genetics professional in my area? in the Handbook.
Where can I find additional information about Wolf-Hirschhorn syndrome?
You may find the following resources about Wolf-Hirschhorn syndrome helpful. These materials are written for the general public.
MedlinePlus – Health information (2 links)
- Genetic and Rare Diseases Information Center – Information about genetic conditions and rare diseases
Educational resources – Information pages (3 links)
Patient support – For patients and families (3 links)
You may also be interested in these resources, which are designed for healthcare professionals and researchers.
What other names do people use for Wolf-Hirschhorn syndrome?
- chromosome 4p deletion syndrome
- chromosome 4p monosomy
- del(4p) syndrome
- 4p Deletion Syndrome
- monosomy 4p
- partial monosomy 4p
- 4p- syndrome
What if I still have specific questions about Wolf-Hirschhorn syndrome?
Where can I find general information about genetic conditions?
The Handbook provides basic information about genetics in clear language.
- What does it mean if a disorder seems to run in my family?
- What is a chromosome?
- Can changes in the number of chromosomes affect health and development?
- Are chromosomal disorders inherited?
These links provide additional genetics resources that may be useful.
What glossary definitions help with understanding Wolf-Hirschhorn syndrome?
cell ; chromosome ; cleft palate ; deletion ; developmental delay ; egg ; embryonic ; failure to thrive ; gene ; hypertelorism ; hypotonia ; microcephaly ; micrognathia ; monosomy ; motor ; motor skill ; muscle tone ; palate ; philtrum ; prevalence ; rearrangement ; reproductive cells ; ring chromosomes ; scoliosis ; seizure ; short stature ; sign ; sperm ; stature ; symptom ; syndrome ; translocation
You may find definitions for these and many other terms in the Genetics Home Reference Glossary.
See also Understanding Medical Terminology.
The resources on this site should not be used as a substitute for professional medical care or advice. Users seeking information about a personal genetic disease, syndrome, or condition should consult with a qualified healthcare professional. See How can I find a genetics professional in my area? in the Handbook.