About Prader-Willi Syndrome
Prader-Willi Syndrome is a neurogenetic disorder where multiple genes on chromosome 15 are either absent or unexpressed. Unlike many other neurogenetic disorders, Prader-Willi Syndrome cannot be inherited. A diagnosis is obtained through genetic testing.
The disorder is characterised by the relatively small stature of the affected individual, including having small hands and feet. As newborns, hypotonia (low muscle tone) is a common physical symptom. This can complicate the birthing process, requiring caesarean sections to be performed. Infants with Prader-Willi Syndrome have reduced levels of limb movement compared to their healthy peers. Hypogonadism (sex hormone deficiency) is often present. Male babies may present with cryptorchidism (undescended testicles) and scrotal hypoplasia (underdeveloped testes). Female babies may present with hypoplasia of the labia minora and clitoris (underdeveloped vagina and clitoris).
As patients reach toddlerhood, obesity becomes the most distinct characteristic of Prader-Willi Syndrome. The syndrome is also the most common genetic cause of obesity, as affected individuals do not receive the signal from their brains that they are satiated, even after they have eaten – this is known as hyperphagia. As a result, affected children feel a constant, strong craving for food which they respond to by eating in excessive amounts.
Cognitive issues associated with Prader-Willi Syndrome
Prader-Willi Syndrome is associated with cognitive issues that range from moderate to profound in severity. The impairments significantly interfere with daily function and patients will often require care even into adulthood.
Individuals with Prader-Willi Syndrome have an average IQ of 70, which is classified under mild mental retardation. This translates into poor academic performance in school, and deficits in cognitive abilities including working memory and sequential processing. On the other hand, they have relatively strong verbal language, visual-spatial and reading skills.
Affected individuals also display behavioural difficulties. These include throwing temper tantrums and engaging in manipulative behaviour as children. With a repetitive behaviour profile, individuals with Prader-Willi Syndrome tend to reject change and prefer strict routines. They show obsessive and compulsive traits, such as picking at their skin or hoarding items, at similar rates to individuals who have been diagnosed with Obsessive-Compulsive Disorder (OCD). A small proportion of patients go on to develop psychiatric disorders with psychotic features as adults.
Treatment for Prader-Willi Syndrome
Treatment for Prada-Wili Syndrome will depend largely on the extent of the impairment. For higher level functioning individuals neurofeedback could be trialled to try and reduce over-arousal symptoms. Behavioural and emotional management can be important and management of obsessive behaviours and coping with change will need some assistance by a psychologist.