National Center for Advancing and Translational Sciences Genetic and Rare Diseases Information Center, a program of the National Center for Advancing and Translational Sciences

Prader-Willi syndrome

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Other Names:
PWS; Willi-Prader syndrome; Prader-Labhart-Willi syndrome
Categories:
Prader-Willi syndrome (PWS) is a genetic condition that affects many parts of the body. Infants with PWS have severe hypotonia (low muscle tone), feeding difficulties, and slow growth. In later infancy or early childhood, affected children typically begin to eat excessively and become obese. Other signs and symptoms often include short stature, hypogonadism, developmental delays, cognitive impairment, and distinctive behavioral characteristics such as temper tantrums, stubbornness, and obsessive-compulsive tendencies. PWS is caused by missing or non-working genes on chromosome 15. Most cases are not inherited and occur randomly. Rarely, a genetic change responsible for PWS can be inherited. Management of PWS generally depends on the affected person's age and symptoms.[1][2]
Last updated: 7/7/2016
In infancy, Prader-Willi syndrome (PWS) is characterized by weak muscle tone (hypotonia), feeding difficulties, poor growth, and delayed development. In later infancy or early childhood, affected children develop an extreme appetite, which leads to overeating and obesity.[2][1]

Other signs and symptoms of PWS may include:[2][1]
  • mild to moderate intellectual disability
  • sleep abnormalities
  • unusually fair skin
  • underdeveloped genitals
  • delayed or incomplete puberty
  • short stature
  • strabismus
  • scoliosis
  • small hands and feet
  • distinctive facial features such as a narrow forehead, almond-shaped eyes, and a triangular mouth

Behavioral problems are common and often include temper tantrums, stubbornness, and obsessive-compulsive tendencies.[2][1]

Last updated: 7/7/2016

This table lists symptoms that people with this disease may have. For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. This information comes from a database called the Human Phenotype Ontology (HPO) . The HPO collects information on symptoms that have been described in medical resources. The HPO is updated regularly. Use the HPO ID to access more in-depth information about a symptom.

Showing of 113 |
Medical Terms Other Names
Learn More:
HPO ID
80%-99% of people have these symptoms
Central hypotonia 0011398
Cryptorchidism
Undescended testis
Undescended testes
[ more ] 		0000028
Delayed speech and language development
Deficiency of speech development
Delayed language development
Delayed speech
Delayed speech acquisition
Delayed speech development
Impaired speech and language development
Impaired speech development
Language delay
Language delayed
Language development deficit
Late-onset speech development
Poor language development
Speech and language delay
Speech and language difficulties
Speech delay
[ more ] 		0000750
Failure to thrive in infancy
Faltering weight in infancy
Weight faltering in infancy
[ more ] 		0001531
Generalized hypotonia
Decreased muscle tone
Low muscle tone
[ more ] 		0001290
Global developmental delay 0001263
Growth hormone deficiency 0000824
Hypogonadotropic hypogonadism 0000044
Infertility 0000789
Motor delay 0001270
Narrow palm 0004283
Polyphagia
Voracious appetite
0002591
Poor suck
Poor sucking
0002033
Short foot
Short feet
Small feet
[ more ] 		0001773
Short palm 0004279
Short stature
Decreased body height
Small stature
[ more ] 		0004322
Specific learning disability 0001328
30%-79% of people have these symptoms
Abdominal obesity
Central obesity
0012743
Abnormal facial shape
Unusual facial appearance
0001999
Abnormal rapid eye movement sleep 0002494
Almond-shaped palpebral fissure
Almond shaped eyes
Almond-shaped opening between the eyelids
[ more ] 		0007874
Attention deficit hyperactivity disorder
Attention deficit
Attention deficit disorder
Attention deficit-hyperactivity disorder
Attention deficits
Childhood attention deficit/hyperactivity disorder
[ more ] 		0007018
Brain imaging abnormality 0410263
Central adrenal insufficiency 0011734
Central sleep apnea 0010536
Clitoral hypoplasia
Small clitoris
Underdeveloped clit
[ more ] 		0000060
Cutaneous photosensitivity
Photosensitive skin
Photosensitive skin rashes
Photosensitivity
Sensitivity to sunlight
Skin photosensitivity
Sun sensitivity
[ more ] 		0000992
Decreased circulating gonadotropin level 0030339
Decreased fetal movement
Less than 10 fetal movements in 12 hours
0001558
Decreased muscle mass 0003199
Decreased testicular size
Small testes
Small testis
[ more ] 		0008734
Delayed puberty
Delayed pubertal development
Delayed pubertal growth
Pubertal delay
[ more ] 		0000823
Diabetes mellitus 0000819
Downturned corners of mouth
Downturned corners of the mouth
Downturned mouth
[ more ] 		0002714
Edema
Fluid retention
Water retention
[ more ] 		0000969
Erysipelas 0001055
Failure to thrive
Faltering weight
Weight faltering
[ more ] 		0001508
Gastroparesis
Delayed gastric emptying
0002578
Hypogonadism
Decreased activity of gonads
0000135
Hypopigmentation of hair
Loss of hair color
0005599
Hypopigmentation of the skin
Patchy lightened skin
0001010
Hypoplastic labia majora
Small labia majora
Underdeveloped vaginal lips
[ more ] 		0000059
Hypoplastic labia minora
Underdeveloped inner lips
0000064
Hyporeflexia
Decreased reflex response
Decreased reflexes
[ more ] 		0001265
Impaired pain sensation
Decreased pain sensation
0007328
Impaired temperature sensation
Abnormality of temperature sensation
Loss of temperature sensation
[ more ] 		0010829
Increased susceptibility to fractures
Abnormal susceptibility to fractures
Bone fragility
Frequent broken bones
Increased bone fragility
Increased tendency to fractures
[ more ] 		0002659
Intellectual disability, borderline
Mental retardation, borderline
0006889
Intellectual disability, mild
Mental retardation, borderline-mild
Mild and nonprogressive mental retardation
Mild mental retardation
[ more ] 		0001256
Kyphosis
Hunched back
Round back
[ more ] 		0002808
Micropenis
Short penis
Small penis
[ more ] 		0000054
Narrow forehead
Decreased width of the forehead
0000341
Narrow nasal bridge
Narrow bridge of nose
Nasal bridge, thin
Nasal Bridge, Narrow
[ more ] 		0000446
Nasal speech
Nasal voice
0001611
Obstructive sleep apnea 0002870
Oligomenorrhea
Light or infrequent menstrual periods
0000876
Osteopenia 0000938
Osteoporosis 0000939
Periodontitis 0000704
Perisylvian polymicrogyria 0012650
Primary amenorrhea 0000786
Recurrent respiratory infections
Frequent respiratory infections
Multiple respiratory infections
respiratory infections, recurrent
Susceptibility to respiratory infections
[ more ] 		0002205
Scoliosis 0002650
Scrotal hypoplasia
Smaller than typical growth of scrotum
0000046
Sleep apnea
Pauses in breathing while sleeping
0010535
Small hand
Disproportionately small hands
0200055
Small pituitary gland 0012506
Strabismus
Cross-eyed
Squint
Squint eyes
[ more ] 		0000486
Thin upper lip vermilion
Thin upper lip
0000219
Ventriculomegaly 0002119
Weak cry 0001612
5%-29% of people have these symptoms
Abnormality of the cerebral white matter 0002500
Autistic behavior 0000729
Carious teeth
Dental cavities
Tooth cavities
Tooth decay
[ more ] 		0000670
Central hypothyroidism 0011787
Decreased inhibin B level 0031100
Esotropia
Inward turning cross eyed
0000565
Excessive daytime sleepiness 0002189
Frontal upsweep of hair
Cowlick
Frontal Cowlick
Upswept frontal hair
[ more ] 		0002236
Hip dysplasia 0001385
Hypertension 0000822
Intellectual disability, moderate
IQ between 34 and 49
0002342
Myopia
Close sighted
Near sighted
Near sightedness
Nearsightedness
[ more ] 		0000545
Nasogastric tube feeding in infancy 0011470
Poor fine motor coordination 0007010
Premature adrenarche 0012412
Premature pubarche
Premature pubic hair growth
0012411
Psychosis 0000709
Radial deviation of finger 0009466
Seizure 0001250
Stroke 0001297
Syndactyly
Webbed fingers or toes
0001159
Temperature instability 0005968
Upslanted palpebral fissure
Upward slanting of the opening between the eyelids
0000582
Vomiting
Throwing up
0002013
Xerostomia
Dry mouth
Dry mouth syndrome
Reduced salivation
[ more ] 		0000217
1%-4% of people have these symptoms
Adrenal insufficiency 0000846
Autism 0000717
Iris hypopigmentation
Light eye color
0007730
Precocious puberty
Early onset of puberty
Early puberty
[ more ] 		0000826
Type II diabetes mellitus
Noninsulin-dependent diabetes
Type 2 diabetes
Type II diabetes
[ more ] 		0005978
Percent of people who have these symptoms is not available through HPO
Acromicria 0031878
Autosomal dominant inheritance 0000006
Clinodactyly
Permanent curving of the finger
0030084
Dolichocephaly
Long, narrow head
Tall and narrow skull
[ more ] 		0000268
Generalized hypopigmentation
Fair skin
Pale pigmentation
[ more ] 		0007513
Genu valgum
Knock knees
0002857
Hyperinsulinemia 0000842
Hypermetropia
Farsightedness
Long-sightedness
[ more ] 		0000540
Hypoventilation
Slow breathing
Under breathing
[ more ] 		0002791
Neonatal hypotonia
Low muscle tone, in neonatal onset
0001319
Poor gross motor coordination 0007015
Sporadic
No previous family history
0003745
Showing of 113 |
Last updated: 7/1/2020
Prader-Willi syndrome (PWS) is caused by the loss of active genes in a specific region of chromosome 15. People normally inherit one copy of chromosome 15 from each parent. Some genes on chromosome 15 are only active (or "expressed") on the copy that is inherited from a person's father (the paternal copy). When genes are only active if inherited from a specific parent, it is called genomic imprinting.

About 70% of cases of PWS occur when a person is missing specific genes on the long arm of the paternal copy of chromosome 15. This is called a deletion. While there are copies of these same genes on the maternal copy of chromosome 15, the maternal copies of these genes are not expressed.
 
In about 25% of cases, PWS is due to a person inheriting only 2 maternal copies of chromosome 15, instead of one copy from each parent. This is called maternal uniparental disomy.

Rarely (in about 2% of cases), PWS is caused by a rearrangement of chromosome material called a translocation, or by a change (mutation) or other defect that abnormally inactivates genes on the paternal chromosome 15.[1]

Each of these genetic changes result in a loss of gene function on part of chromosome 15, likely causing the characteristic features of PWS.[1]
Last updated: 7/7/2016
Most cases of Prader-Willi syndrome (PWS) are not inherited and are due to random events during the formation of egg or sperm cells, or in early fetal development. This is usually the case when PWS is caused by a deletion in the paternal chromosome 15, or by maternal uniparental disomy. However in rare cases, a genetic change responsible for PWS can be inherited.[1]

The risk to family members of a person with PWS depends on the genetic cause of the condition in the affected person.[2] Because the various genetic causes of PWS are complex, people seeking information about specific risks to themselves or family members are encouraged to speak with a genetics professional.
Last updated: 7/7/2016
There are clinical diagnostic criteria for Prader-Willi syndrome (PWS) that were developed in the past that continue to be useful. These criteria can be viewed on the National Institute of Health's NICHD Web site.

However, the current mainstay of a diagnosis when PWS is suspected is a form of genetic testing called DNA methylation testing. This testing can detect abnormal, parent-specific imprinting on the region of chromosome 15 that is responsible for PWS. It determines whether the region is maternally inherited only (i.e., the paternally contributed region is absent) and confirms a diagnosis in more than 99% of affected people. DNA methylation testing is especially important in people who have non-classic features, or are too young to show enough features to make the diagnosis based on signs and symptoms alone.[2][3]
Last updated: 7/7/2016

Testing Resources

  • The Genetic Testing Registry (GTR) provides information about the genetic tests for this condition. The intended audience for the GTR is health care providers and researchers. Patients and consumers with specific questions about a genetic test should contact a health care provider or a genetics professional.
A multidisciplinary team approach is ideal for the treatment of people with Prader-Willi syndrome (PWS). Early diagnosis, early multidisciplinary care, and growth hormone treatment have greatly improved the quality of life of many affected children. In general, management of this condition depends on the affected person's age and symptoms.[2][3]

When a diagnosis of PWS is made, several evaluations are needed to assess the extent of the condition. For example, newborns should be assessed for sucking problems; infants should be assessed for development; and young children should have a vision exam. All males should be evaluated for the presence of cryptorchidism. Other associated conditions for which evaluations may be recommended include hypothyroidism, scoliosis, behavioral problems, psychosis, and respiratory problems and sleep issues.[2][3]

In infants, special feeding techniques may be needed. Young children often need early intervention, including physical therapy for muscle strength and reaching physical milestones, and speech therapy for language issues. Cryptorchidism may resolve on its own but usually requires hormonal and/or surgical treatment. When excessive eating begins and weight percentiles increase, affected children should be on a program of a well-balanced diet, exercise, and close supervision with food. A consultation with a dietitian is recommended. Behavioral problems may be addressed with special behavioral management programs. Serotonin uptake inhibitors have helped many affected teenagers and adults, particularly those with obsessive-compulsive symptoms.[2][3]

Growth hormone treatment can normalize height, increase lean body mass, increase mobility, and decrease fat mass. Controlled trials of growth hormone therapies have shown significant benefit from infancy through adulthood. Benefits may include an increase in language and cognitive skills, and better motor performance. Sex hormone replacement helps to produce secondary sex characteristics (those that develop during puberty) but is somewhat controversial due to possible behavior problems in males, risk of stroke, and hygiene concerns related to menstruation in females.[2][3]

Clinical trials investigating potential treatment options for people with PWS are ongoing. ClinicalTrials.gov provides patients, family members, and members of the public with current information on clinical research studies for PWS. Use each study's contact information to learn more.
Last updated: 7/7/2016

Management Guidelines

  • The Foundation for Prader-Willi Research provides an overview of diagnosis and treatment for Prader-Willi syndrome.
  • Project OrphanAnesthesia is a project whose aim is to create peer-reviewed, readily accessible guidelines for patients with rare diseases and for the anesthesiologists caring for them. The project is a collaborative effort of the German Society of Anesthesiology and Intensive Care, Orphanet, the European Society of Pediatric Anesthesia, anesthetists and rare disease experts with the aim to contribute to patient safety.

FDA-Approved Treatments

The medication(s) listed below have been approved by the Food and Drug Administration (FDA) as orphan products for treatment of this condition. Learn more orphan products.

  • Somatropin (r-DNA) for injection (Brand name: Genotropin) - Manufactured by Pfizer, Inc.
    FDA-approved indication: Long-term treatment of pediatric patients who have growth failure due to Prader-Willi syndrome (PWS). (Genotropin is not appropriated for all children with PWS, so please talk to your doctor.)
    National Library of Medicine Drug Information Portal
Children with Prader-Willi syndrome (PWS) can be mainstreamed into the classroom environment, although they need additional speech therapy and should have additional physical activity periods in place of rest periods. They generally need a structured environment and may need a smaller classroom size for individual attention.[4]

People with PWS usually reach adulthood and are able to function in a group home setting, performing vocational work, or attending community college classes.[4] According to the Prader-Willi Syndrome Association, people with PWS can expect to accomplish many of the things their peers do. However, they do need a significant amount of support from their families and from school, work, and residential service providers. Even those with IQs in the normal range need lifelong diet supervision and protection from food availability.[5]

Complications that could affect the quality of life and potentially shorten life expectancy include those relating to hypogonadism, behavioral or psychological issues, and morbid obesity.[4]
Last updated: 1/6/2015

If you need medical advice, you can look for doctors or other healthcare professionals who have experience with this disease. You may find these specialists through advocacy organizations, clinical trials, or articles published in medical journals. You may also want to contact a university or tertiary medical center in your area, because these centers tend to see more complex cases and have the latest technology and treatments.

If you can’t find a specialist in your local area, try contacting national or international specialists. They may be able to refer you to someone they know through conferences or research efforts. Some specialists may be willing to consult with you or your local doctors over the phone or by email if you can't travel to them for care.

You can find more tips in our guide, How to Find a Disease Specialist. We also encourage you to explore the rest of this page to find resources that can help you find specialists.

Healthcare Resources

Related diseases are conditions that have similar signs and symptoms. A health care provider may consider these conditions in the table below when making a diagnosis. Please note that the table may not include all the possible conditions related to this disease.

Conditions with similar signs and symptoms from Orphanet
At birth, genetic testing should be used to exclude other causes of hypotonia. If the neonatal phenotype evokes PWS and the genetics are negative, genes for the Prader-Willi-like syndrome (PWS-like) should be searched. In older individuals, the differential diagnosis is of other syndromic obesities such as Bardet-Biedl syndrome, Alström syndrome and, particularly, PWS-like.
Visit the Orphanet disease page for more information.

Research helps us better understand diseases and can lead to advances in diagnosis and treatment. This section provides resources to help you learn about medical research and ways to get involved.

Clinical Research Resources

  • ClinicalTrials.gov lists trials that are related to Prader-Willi syndrome. Click on the link to go to ClinicalTrials.gov to read descriptions of these studies.

    Please note: Studies listed on the ClinicalTrials.gov website are listed for informational purposes only; being listed does not reflect an endorsement by GARD or the NIH. We strongly recommend that you talk with a trusted healthcare provider before choosing to participate in any clinical study.

Patient Registry

  • A registry supports research by collecting of information about patients that share something in common, such as being diagnosed with Prader-Willi syndrome. The type of data collected can vary from registry to registry and is based on the goals and purpose of that registry. Some registries collect contact information while others collect more detailed medical information. Learn more about registries.

    Registries for Prader-Willi syndrome:
    Global Prader-Willi Syndrome Registry
     

Support and advocacy groups can help you connect with other patients and families, and they can provide valuable services. Many develop patient-centered information and are the driving force behind research for better treatments and possible cures. They can direct you to research, resources, and services. Many organizations also have experts who serve as medical advisors or provide lists of doctors/clinics. Visit the group’s website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD.

Organizations Supporting this Disease

Living with a genetic or rare disease can impact the daily lives of patients and families. These resources can help families navigate various aspects of living with a rare disease.

Education Resources

  • The Genetics Education Materials for School Success (GEMSS) aims to assure that all children with genetic health conditions succeed in school-life. Their Web site offers general and condition-specific education resources to help teachers and parents better understand the needs of students who have genetic conditions.

These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

Where to Start

In-Depth Information

  • GeneReviews provides current, expert-authored, peer-reviewed, full-text articles describing the application of genetic testing to the diagnosis, management, and genetic counseling of patients with specific inherited conditions.
  • Medscape Reference provides information on this topic. You may need to register to view the medical textbook, but registration is free.
  • The Monarch Initiative brings together data about this condition from humans and other species to help physicians and biomedical researchers. Monarch’s tools are designed to make it easier to compare the signs and symptoms (phenotypes) of different diseases and discover common features. This initiative is a collaboration between several academic institutions across the world and is funded by the National Institutes of Health. Visit the website to explore the biology of this condition.
  • Online Mendelian Inheritance in Man (OMIM) is a catalog of human genes and genetic disorders. Each entry has a summary of related medical articles. It is meant for health care professionals and researchers. OMIM is maintained by Johns Hopkins University School of Medicine. 
  • Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.
  • PubMed is a searchable database of medical literature and lists journal articles that discuss Prader-Willi syndrome. Click on the link to view a sample search on this topic.

Questions sent to GARD may be posted here if the information could be helpful to others. We remove all identifying information when posting a question to protect your privacy. If you do not want your question posted, please let us know. Submit a new question

  • I'm pregnant and my brother has Prader-Willi syndrome. What is the chance of my child having the same condition? Can it be hereditary and can I test for it before my child is born? See answer

  • My foster child will be tested for Prader-Willi syndrome, but has a very high IQ. Is it possible for people with Prader-Willi to have high IQs?   See answer

  • Does the menstrual cycle happen earlier in Prader-Willi syndrome? See answer

  • For individuals with Prader Willi syndrome, how does this condition affect their lives when they get older? See answer


  1. Prader-Willi syndrome. Genetics Home Reference. June 2014; https://ghr.nlm.nih.gov/condition/prader-willi-syndrome#.
  2. Driscoll DJ, Miller JL, Schwartz S, and Cassidy SB. Prader-Willi Syndrome. GeneReviews. February 4 2016; http://www.ncbi.nlm.nih.gov/books/NBK1330/.
  3. Prader-Willi syndrome Diagnosis and Treatments. Foundation for Prader-Willi Research. https://www.fpwr.org/prader-willi-syndrome-diagnosis-treatments/. Accessed 7/7/2016.
  4. Ann Scheimann. Prader-Willi Syndrome. Medscape. March 18, 2014; http://emedicine.medscape.com/article/947954-overview. Accessed 1/6/2015.
  5. FAQ. Prader-Willi Syndrome Association. 2015; http://www.pwsausa.org/about-pws/faq. Accessed 9/23/2015.