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Prader-Willi syndrome


Other Names for this Disease

  • Obesity, muscular hypotonia, mental retardation, short stature, hypogonadotropic hypogonadism, and small hands and feet
  • Prader Labhart Willi syndrome
  • PWS
  • Willi-Prader syndrome
See Disclaimer regarding information on this site. Some links on this page may take you to organizations outside of the National Institutes of Health.

Symptoms

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What are the signs and symptoms of Prader-Willi syndrome?

Prader-Willi syndrome is considered a spectrum disorder, meaning not all symptoms will occur in everyone affected and the symptoms may range from mild to severe. There are generally two stages of symptoms for people with Prader-Willi syndrome [1]:

  • Stage 1 -- As newborns with Prader-Willi can have low muscle tone, which can affect their ability to suck properly. As a result, these babies may need special feeding techniques to help them eat. Infants may also have problems gaining weight. As these babies grow older, their strength and muscle tone usually get better. They meet motor milestones, but are usually slower in doing so.

  • Stage 2 -- Between the ages of 1 and 6, the disorder changes to one of constant hunger and food seeking. Most people with Prader-Willi syndrome have an insatiable appetite, meaning they never feel full.  In fact, their brains are telling them they are starving.  They may have trouble regulating their own eating and may need external restrictions on food, including locked kitchen and food storage areas. This problem is made worse because people with Prader-Willi syndrome use fewer calories than those without the syndrome because they have less muscle mass.  The combination of eating massive amounts of food and not burning enough calories can lead to life-threatening obesity if the diet is not kept under strict control.[1]

There are other symptoms that may affect people with Prader-Willi, including [1]:

  • Behavioral problems, usually during transitions and unanticipated changes, such as stubbornness or temper tantrums
  • Delayed motor skills and speech due to low muscle tone 
  • Cognitive problems, ranging from near normal intelligence to mild mental retardation; learning disabilities are common
  • Repetitive thoughts and verbalizations
  • Collecting and hoarding of possessions
  • Picking at skin
  • Low sex hormone levels

Many people with this disorder also have distinctive facial features and short stature. The genitals in both males and females are underdeveloped, and most affected individuals are unable to conceive children (infertile). Additionally, some people with Prader-Willi syndrome have unusually fair skin and light-colored hair.[2]
Last updated: 4/1/2011

The Human Phenotype Ontology provides the following list of signs and symptoms for Prader-Willi syndrome. If the information is available, the table below includes how often the symptom is seen in people with this condition. You can use the MedlinePlus Medical Dictionary to look up the definitions for these medical terms.

Signs and Symptoms Approximate number of patients (when available)
Delayed speech and language development 90%
Failure to thrive in infancy 90%
Generalized hypotonia 90%
Growth hormone deficiency 90%
Hypogonadotrophic hypogonadism 90%
Infertility 90%
Motor delay 90%
Narrow palm 90%
Obesity 90%
Polyphagia 90%
Poor suck 90%
Short foot 90%
Short palm 90%
Short stature 90%
Specific learning disability 90%
Cryptorchidism 85%
Attention deficit hyperactivity disorder 75%
Scrotal hypoplasia 69%
Adrenal insufficiency 60%
Primary amenorrhea 56%
Abnormality of chromosome segregation 50%
Abnormality of dental enamel 50%
Abnormality of the palate 50%
Almond-shaped palpebral fissure 50%
Behavioral abnormality 50%
Brachydactyly syndrome 50%
Clinodactyly of the 5th finger 50%
Clitoral hypoplasia 50%
Cognitive impairment 50%
Cutaneous photosensitivity 50%
Decreased muscle mass 50%
Delayed puberty 50%
Delayed skeletal maturation 50%
Downturned corners of mouth 50%
Glomerulopathy 50%
Hypoplasia of penis 50%
Hypoplasia of the ear cartilage 50%
Hypoplastic labia minora 50%
Incoordination 50%
Intrauterine growth retardation 50%
Kyphosis 50%
Micropenis 50%
Muscular hypotonia 50%
Narrow forehead 50%
Narrow nasal bridge 50%
Nasal speech 50%
Recurrent respiratory infections 50%
Scoliosis 50%
Seizures 50%
Single transverse palmar crease 50%
Sleep apnea 50%
Strabismus 50%
Telecanthus 50%
Type I diabetes mellitus 50%
Hypopigmentation of hair 33%
Hypopigmentation of the skin 33%
Impaired pain sensation 33%
Iris hypopigmentation 33%
Oligomenorrhea 33%
Ventriculomegaly 33%
Type II diabetes mellitus 25%
Autism 19%
Psychosis 15%
Hip dysplasia 10%
Carious teeth 7.5%
Esotropia 7.5%
Frontal upsweep of hair 7.5%
Myopia 7.5%
Osteopenia 7.5%
Osteoporosis 7.5%
Poor fine motor coordination 7.5%
Radial deviation of finger 7.5%
Syndactyly 7.5%
Temperature instability 7.5%
Upslanted palpebral fissure 7.5%
Precocious puberty 4%
Clinodactyly -
Decreased fetal movement -
Dolichocephaly -
Generalized hypopigmentation -
Hyperinsulinemia -
Hypermetropia -
Hypoventilation -
Poor gross motor coordination -
Sporadic -

Last updated: 12/1/2014

The Human Phenotype Ontology (HPO) has collected information on how often a sign or symptom occurs in a condition. Much of this information comes from Orphanet, a European rare disease database. The frequency of a sign or symptom is usually listed as a rough estimate of the percentage of patients who have that feature.

The frequency may also be listed as a fraction. The first number of the fraction is how many people had the symptom, and the second number is the total number of people who were examined in one study. For example, a frequency of 25/25 means that in a study of 25 people all patients were found to have that symptom. Because these frequencies are based on a specific study, the fractions may be different if another group of patients are examined.

Sometimes, no information on frequency is available. In these cases, the sign or symptom may be rare or common.


References
  1. Prader-Willi Syndrome. National Institute of Child Health and Human Development (NICHD). March 24, 2010; http://www.nichd.nih.gov/health/topics/Prader_Willi_Syndrome.cfm. Accessed 3/24/2011.
  2. Prader-Willi syndrome. Genetics Home Reference (GHR). July 2011; http://ghr.nlm.nih.gov/condition=praderwillisyndrome. Accessed 4/30/2014.


Other Names for this Disease
  • Obesity, muscular hypotonia, mental retardation, short stature, hypogonadotropic hypogonadism, and small hands and feet
  • Prader Labhart Willi syndrome
  • PWS
  • Willi-Prader syndrome
See Disclaimer regarding information on this site. Some links on this page may take you to organizations outside of the National Institutes of Health.