Introduction to Prader-Willi Syndrome

What is Prader-Willi Syndrome?

 Video courtesy of One SMALL Step, Canada
Video courtesy NHS UK. Click to view (external website)

Video courtesy NHS UK. Click to view (external website)

PWS is a complex genetic disorder that typically causes low muscle tone, short stature, incomplete sexual development, cognitive disabilities, problem behaviors, and a chronic feeling of hunger that can lead to excessive eating and life-threatening obesity. The condition, which is caused by the absence of certain genes on chromosome 15, was first described in 1956 by Swiss doctors Prader, Willi and Labhart.

What are the common features of PWS?

Individuals with PWS have generally similar features but the number and degree of severity of them may vary. Babies born with PWS are often described as being ‘floppy’, which is due to hypotonia (low muscle tone), which often results in feeding difficulties and weight gain. Children with PWS often show distinctive facial features including a narrow face, almond-shaped eyes, small hands and feet and a smaller than average mouth.

How is PWS diagnosed?

If an infant displays signs such as poor muscle tone, feeding problems, smaller than usual hands or feet, testing for PWS is usually performed. There are several genetic tests that can confirm PWS. Suspicion of the diagnosis is first assessed clinically, then confirmed by a specialised genetic testing on a blood sample.

How common is PWS?

It is estimated that one in 12,000 to 15,000 people has PWS. In Ireland, in excess of 100 cases of PWS have been diagnosed. PWS is found in people of both sexes and all races.

Is PWS hereditary?

Most cases of PWS are attributed to a spontaneous genetic error that occurs at or near the time of conception for unknown reasons. In a very small number of cases (2% or less), a genetic mutation that does not affect the parent is passed on to the child, and in these families, more than one child may be affected.

What causes PWS patients to constantly feel hungry?

People with PWS have a flaw in the hypothalamus part of their brain, which normally controls feelings of hunger and fullness. While the problem is not yet fully understood, it is apparent that people with this flaw are less likely to feel full; they have a continuous urge to eat which they find difficult to control. To compound this problem, people with PWS need less food because their bodies have less muscle tone and tend to burn fewer calories, so they tend to put on weight more easily.

Does the overeating associated with PWS begin at birth?

No, in fact newborns with PWS often cannot get enough nourishment because low muscle tone impairs their sucking ability. Many require special feeding techniques or tube feeding for several months after birth until muscle control improves. Sometimes in the following years, children with PWS develop an intense interest in food and can quickly gain excess weight if calories are not restricted.

What kind of behavioural problems do people with PWS have?

In addition to their involuntary focus on food, people with PWS tend to have obsessive/compulsive behaviours that are not related to food, such as repetitive thoughts and verbalisations, collecting and hoarding of possessions, picking at skin irritations, and a strong need for routine and predictability. Frustrations or changes in plans can easily set off a loss of emotional control in someone with PWS, ranging from tears to temper tantrums to physical aggression. While medication can help some individuals, minimising difficult behaviour is best managed through careful structuring of the person’s environment and consistent use of positive behaviour management and support.

What kind of future can people with PWS and their families expect?

PWS cannot be outgrown, but with help, people with PWS may expect to accomplish many of the things their ‘normal’ peers do – complete school, achieve in their interests, be a productive worker under the right conditions, even move away from their family home. They do, however, need a significant amount of support from their families and from school, work and residential service providers to both achieve these goals and to avoid obesity and the very serious health consequences that accompany it. Even for those with an IQ within the normal range, lifelong diet supervision and protection from food availability is needed. Although in the past many people with PWS died in adolescence or young adulthood, prevention of obesity can enable those with PWS to have a normal life span. New medications, such as growth hormone, are already improving the quality of life for many people with PWS. With early diagnosis and medical intervention and support, people with PWS can lead a happy and meaningful life, and contribute to the community and society.

What support services are available for people with PWS and their families?

At various stages during their lives people with PWS typically requirement therapeutic assistance from physiotherapists, occupational therapists, speech and language therapists, dieticians, orthotists as well as a range of medical specialists.  Furthermore, their families and carers may require significant practical and emotional support.

Graifin House, a dedicated community residential service set up and run in Dublin by RehabCare in 2003, offers residential care to six young adults with PWS. Through the support of RehabCare and appropriate linkages with the acute sector and local community, each individual gets the opportunity to maximise their own quality of life and contribute to society. Those at Graifin House live a regulated lifestyle with an emphasis on a healthy diet and regular exercise.

What educational needs do people with PWS have?

In the past, children with PWS were generally directed towards special schools that catered only for children with special needs. In recent years with the move towards integrating children with special needs into mainstream schools, parents have been able to explore other options for educating their child with PWS. Some children with PWS do very well in special schools and some children do very well in mainstream schools.

Regardless of their intellectual ability, PWS children need constant supervision in school to ensure that they do not have inappropriate access to food. They may need assistance with their school work.  Because of physically challenges such as their small size, weak muscle tone and weight, they may also need assistance both in the classroom, in PE and in the playground. They may also need a range of behavioural and emotional supports.