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Prader-Willi Syndrome

Prader-Willi Syndrome (PWS) is an inherited disorder genetic disorder which is generally caused by a deletion in Chromosome 15. The features of this disorder includes short stature, mental retardation or learning disabilities, incomplete sexual development, characteristic behavior problems, and an insatiable appetite. The syndrome was first described in 1956 by Drs. Prader, Labhart, and Willi.

The following is an overview of characteristics common to Prader-Willi Syndrome. However, not all symptoms are present in all individuals and the intensity of characteristics varies from person to person.

Craniofacial Anomies which include; almond-shaped eyes, narrow-bifrontal diameter, strabismus and early dental caries/enamel hypoplasia.

Feeding problems in infancy with need for special feeding techniques and poor weight gain/failure to thrive.

Excessive or rapid weight gain after 12 months of age but before 6 years of age resulting in obesity and an obsession with food.

Developmental delays in a child younger than 6 years of age with mild to moderate mental retardation or learning problems in older children.

Genital hypoplasia - for males, scrotal hypoplasia, cryptorchidism, small penis and/or testes for age. For females an absence or severe hypoplasia of labia minora and/or clitoris.

Sexual maturity not fully developed. The child with PWS will begin puberty, but not complete it. This results in delayed or incomplete gonadal maturation with delayed pubertal signs in the absence of intervention after 16 years of age. In males, small gonads, decreased facial and body hair, lack of voice change and in females, amenorrhea/oligomenorrhea after aged 16. This is known as 'precocious puberty' there will be a development in body hair, some breast development in girls and a degree of penile development in boys. Menstruation is often scanty and irregular.

Associated Features:

Sleep disturbance or sleep apnoea.
Hypopigmentation - fair skin and hair compared to family.
Eye abnormalities (esotropia, myopia).
Speech articulation defects.
Small hands and/or feet for height age.
Personality Problems.

Differential Diagnosis:

Some disorders have similar symptoms. The clinician, therefore, in his diagnostic attempt, has to differentiate against the following disorders which need to be ruled out to establish a precise diagnosis.

To Be Identified


May be associated with environmental factors however current research has shown that the PWS results mainly from one of 4 different genetic abnormalities. These are:

A small deletion on chromosome 15.

Chromosome 15 maternal disomy.

A translocation of chromosomes involving chromosome 15.

An error in the imprinting of Chromosome 15.


There is no cure for PWS therefore early diagnosis gives parents an opportunity to manage their child's diet and avoid obesity and its related problems from the start. However for children with this disorder it is best to take the multidisciplinary approach and involve the specialties offered by Pediatrics, Neurology, Endocrinology, Ophthalmology and Orthopedics.

Counseling and Psychotherapy [ See Therapy Section ]:

Most infants will benefit greatly from these early interventions with a with appropriate therapists who can help set up a program to encourage development and provide assistive devices which will help.


DSM Code


Q87.1 Prader-willi Syndrome

Disorder Sheets

Prader-Willi Syndrome
Association (UK)

125a London Road
Derby DE1 2QQ
Tel: +441332365676
Email: Click Here
Website: Click Here

Recommended Book

Prader-Willi Syndrome: A Practical Guide - Click to View


Prader-Willi Syndrome

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