II. Epidemiology

  1. Incidence: 1 in 16,000 births
  2. Most common form of Genetic Syndrome related Obesity

III. Pathophysiology

  1. Associated with defect on long arm of Chromosome 15

IV. Signs

  1. Newborn
    1. Hypotonia
    2. Poor sucking reflex
    3. Diminished cry
    4. Somnolence
  2. Infant
    1. Feeding difficulties and Failure to Thrive
    2. Increased eating starts after 1 year
  3. Early childhood (ages 1 to 6)
    1. Hyperphagia
    2. Rapid weight gain
  4. Classic dysmorphic facial features
    1. Narrow face at temples
    2. Almond shaped eyes
    3. Mouth corners turn downward
    4. Narrow nasal bridge
    5. Strabismus
    6. Thin upper lip
  5. Other features
    1. Morbid Obesity (onset after 12 months)
    2. Developmental delay and learning disabilities
    3. Short Stature
    4. Hypogonadism (e.g. Cryptorchidism, small Testes)
    5. Skin Hypopigmentation

V. Labs: Genetic testing

  1. Indications: All suspected cases of Prader-Willi
  2. Test Sensitivity: 100%
  3. Tests (both are done)
    1. High resolution karyotype
    2. Methylation analysis (specific for PWS)

VI. Associated conditions

VII. Management

  1. Consultations
    1. Ophthalmology for Strabismus and Myopia
    2. Pediatric endocrinology for possible Growth Hormone
    3. Developmental pediatrician
    4. Speech therapy
    5. Physical therapy and occupational therapy
  2. Conditions to observe for and manage
    1. Failure to Thrive as infant
    2. Hypoventilation
    3. Respiratory infections
  3. Preventive strategies
    1. Closely supervise dietary intake
    2. Daily Physical Activity

VIII. Resources

  1. Prader-Willi Syndrome Association
    1. http://www.pwsausa.org

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Ontology: Prader-Willi Syndrome (C0032897)

Definition (MEDLINEPLUS)

Prader-Willi Syndrome (PWS) is a rare genetic disorder. It causes poor muscle tone, low levels of sex hormones and a constant feeling of hunger. The part of the brain that controls feelings of fullness or hunger does not work properly in people with PWS. They overeat, leading to obesity.

Babies with PWS are usually floppy, with poor muscle tone, and have trouble sucking. Boys may have undescended testicles. Later, other signs appear. These include

  • Short stature
  • Poor motor skills
  • Weight gain
  • Underdeveloped sex organs
  • Mild intellectual and learning disabilities

There is no cure for PWS. Growth hormone, exercise, and dietary supervision can help build muscle mass and control weight. Other treatments may include sex hormones and behavior therapy. Most people with PWS will need specialized care and supervision throughout their lives.

NIH: National Institute of Child Health and Human Development

Definition (NCI) A genetic syndrome caused by deletions or disruptions of chromosome 15. It is characterized by reduced fetal activity, mental retardation, hypotonia, short stature, and hypogonadism.
Definition (MSH) An autosomal dominant disorder caused by deletion of the proximal long arm of the paternal chromosome 15 (15q11-q13) or by inheritance of both of the pair of chromosomes 15 from the mother (UNIPARENTAL DISOMY) which are imprinted (GENETIC IMPRINTING) and hence silenced. Clinical manifestations include MENTAL RETARDATION; MUSCULAR HYPOTONIA; HYPERPHAGIA; OBESITY; short stature; HYPOGONADISM; STRABISMUS; and HYPERSOMNOLENCE. (Menkes, Textbook of Child Neurology, 5th ed, p229)
Definition (CSP) congenital neurobehavioral disorder characterized by rounded face, low forehead, almond shaped eyes, squinting, hypogonadism, hypotonia, insatiable appetite leading to obesity, and mental retardation; chromosomal disorder usually associated with a deletion of the proximal portion of the long arm of chromosome 15.
Concepts Congenital Abnormality (T019)
MSH D011218
ICD9 759.81
ICD10 Q87.1
SnomedCT 205794007, 89392001
English Syndrome, Prader-Willi, Prader Willi syndrome, PWS, PRADER-WILLI SYNDROME, PRADER-LABHART-WILLI SYNDROME, Prader-Willi syndrome (diagnosis), Labhart Willi Prader Fanconi Syndrome, Labhart-Willi-Prader-Fanconi Syndrome, Syndrome, Labhart-Willi-Prader-Fanconi, Labhart Willi Syndrome, Labhart-Willi Syndrome, Syndrome, Labhart-Willi, Prader-willi syndrome, Syndrome, Willi-Prader, Willi Prader Syndrome, Willi-Prader Syndrome, Prader Labhart Willi Syndrome, Prader-Willi Syndrome [Disease/Finding], syndrome prader-willi, prader syndrome willy, prader willis syndrome, prader willi syndrome, prader syndrome willis, prader willi syndromes, syndrome willi prader, prader syndrome willi, prader willies syndrome, prader syndrome willies, prader willy syndrome, prader-willi syndrome, willi prader syndrome, Prader-Willi Syndrome, Prader-Labhart-Willi Syndrome, Syndrome, Prader-Labhart-Willi, Prader - Willi syndrome, Prader-Willi syndrome, Prader-Willi syndrome (disorder), Prader-Willi, Prader Willi Syndrome
Japanese プラダーウィリ症候群, プラダーウィリショウコウグン, プラダー・ウィリ症候群, プラーダー-ヴィリ症候群, プラーダー・ウィリ症候群, プラーダー・ウィリー症候群, プラーダー・ヴィリ症候群, Prader-Willi症候群
Swedish Prader-Willis syndrom
Czech Praderové-Williho syndrom, Prader-Labhart-Willi syndrom, Prader-Willi syndrom, Praderův-Labhartův-Williho-Fanconiho syndrom, Praderův-Williho syndrom, Prader-Williho syndrom
Finnish Prader-Willin oireyhtymä
Russian PRADERA-VILLI SINDROM, ПРАДЕРА-ВИЛЛИ СИНДРОМ
Italian Sindrome di Labhart-Willi, Sindrome di Prader-Labhart-Willi-Fanconi, Sindrome di Prader-Willi
Croatian PRADER-WILLIJEV SINDROM
French SPW (Syndrome de Prader-Willi), Syndrome de Prader-Willi, Syndrome de Prader-Labhart-Willi
Polish Zespół Pradera-Williego
Hungarian Prader-Willi-syndroma
Norwegian Prader-Willi-syndrom
Spanish síndrome de Prader - Willi (trastorno), síndrome de Prader - Willi, Síndrome de Labhart-Willi, Síndrome de Prader-Willi
Dutch syndroom van Prader-Willi, Prader-Willi-syndroom, Syndroom, Prader-Willi-
German Prader-Willi Syndrom, Prader-Labhart-Willi-Fanconi-Syndrom, Prader-Willi-Syndrom, Labhart-Willi-Syndrom
Portuguese Síndrome de Labhart-Willi, Síndrome de Prader-Willi