Prader Willi Syndrome

The Prader-Willi Syndrome (PWS) affects both males and females and appears to be present in all races. It is characterised by extreme floppiness at birth caused by low muscle tone (hypotonia). Hypotonia is usually so severe that tube-feeding is necessary at birth, and up to several weeks afterwards, but in a few cases tube-feeding is not needed. Poor sucking ability and sleepiness mean that babies often show little interest in food, and there is a subsequent failure to thrive in the early months of life which can sometimes continue to the toddler stage and beyond. Immature sexual development (hypogonadism) is evident from birth, but is more evident in males as they have undescended testes.

Following the failure to thrive phase, from early childhood (about age 1-4 year), interest in food and appetite increase markedly, and over-eating (hyperphagia) can result. This, usually together with poor muscle tone, can cause severe and life-threatening obesity unless a life-long reduced calorie (energy-controlled) diet is maintained at an appropriate level for each individual. This is true for everyone who has PWS - there are no exceptions - although some individuals may find it easier to keep to a reduced calorie diet than others. Individual needs vary from person to person with regard to energy intake, and calculations regarding daily calorie levels should be made with advice from a dietitian. Later in life, the presence of varying degrees of learning disability, delayed or immature secondary sexual development, and immature emotional and social abilities, all become apparent.

It is thought that most of the symptoms of PWS result from a dysfunction in a part of the brain know as the hypothalamus, which controls many of the hormone functions of the body. It is currently immpossible to examine the hypothalamus in a living person, and research must rely on the generosity of those with PWS and their relatives who donate their brain tissue to research after their death. Details of the brain tissue donor programme are available from the PWSA (UK).

OTHER CHARACTERISTICS IN PWS

The following characteristics, both physical and psychological, may occur in PWS. Not every characteristic is present in every individual, and they can vary in intensity from mild to severe. They may also very each individual at different times or in different circumstances.

Physical

• Generally short stature, with very small hands and feet (size 2 or under in females, size 5 and under in males), although there are no exceptions. Those who have had been treated with growth hormones are more likely to be taller and have larger hands and feet. Equally those who have tall parents are more likely to be taller than average for PWS.
• Curvature of the spine (most commonly scoliosis, also lordosis and kyphosis).
• Undescended testes in males/very small penis
• Absent or irregular periods in females
• Excessive day-time sleepiness and disorded night-time sleep patterns
• Repeated momentary cessation of breathing whilst asleep (sleep apnoea)
• Squint (strabismus) (usually correctable with surgery in childhood or with spectacles) and other visual impairments.
• High pain threshold, with decreased sensitivity to injury or disease
• Easy bruising
• Poor body thermostat, and poor sensitivity to altered temperatures
• Thinning of the bones (osteoporosis) in both males and females, due to lack of sex hormornes and reduced exercise
• Constipation and/or diarrrhoea
• Speech and language disabilities (in expression and/or comprehension)
• Tooth surface loss
• Epilepsy (in a small majority, but thought to be no more common than in the general population).

Pyschological

• A delayed or underdeveloped emotional and social level which causes the person to function at the emotional level of a young child, as can be seen from some of the characteristics given below:
• Emotional outbursts of rage or prolonged crying (including, in some cases aggressive behaviour towards objects, self and/or other people)
• Obsessive and/or compulsive behaviour (often with regard to food, but can also be other topics or people)
• skin picking (also requires physical treatment for wounds incurred by this)
• Argumentative or oppositional behaviour
• Stubbornness
• Difficulty in adaptinig to changes in routine
• Manipulative behaviour
• Attention-seeking behaviour
• “Stealing” and “lying”
• Mental health problems, including depression and anxiety. there is increasing evidence that a minority of people with PWS are liable to have a psychotic illness, which can have a very sudden onset. A recent report has found this to be much more common in those with the disomy form of PWS (Boer et al, 2002).