Prader-Willi Syndrome presents with many symptoms that can affect a person’s physical, psychological, cognitive and behavioural development. While some symptoms are more common than others, we have outlined the more common symptoms that affect people with PWS below.

Increased appetite and high propensity to obesity

One of the most well-known symptoms of PWS is the constant craving for food. People with PWS do not experience normal satiety (feeling of fullness) which, when unmanaged, often leads to overeating and obesity.

This symptom normally starts at around age 2 and can be accompanied by other behavioural issues related to eating such as hiding and hoarding food.

Low muscle mass and muscle tone

A key sign during infancy of PWS is poor muscle tone. This can appear in babies and infants as the ‘floppiness’ of limbs which is especially apparent when being held. The medical term for this symptom is hypotonia and can also present in the following ways: 

• poor reflexes, including suck reflexes when nursing
• weak cry
• limited range of movement

Behavioural and mental health issues

People with PWS often display a number of behavioural issues that can result in temper tantrums. Other behavioural issues include: 

• strict adherence to routines
• obsessive compulsive or repetitive tendencies
• controlling or manipulative tendencies
• mental health issues such as depression and anxiety, often accompanied by skin picking

Learning difficulties

Mild to moderate intellectual disability is common for people with PWS, which often means it is difficult for a child with PWS to reach developmental milestones. Problem solving and reasoning are commonly affected. 

Other symptoms of Prader-Willi Syndrome

While the common symptoms of PWS have been outlined above, the following symptoms may also be present in someone who has PWS:

• speech difficulties
• gastric complications like constipation, poor digestion and slow gastric emptying
• poor temperature sensation and regulation
• high pain threshold – making it difficult to diagnose illness
• high threshold for vomiting
• slow sensory reception and processing
• scoliosis or kyphosis
• thick saliva and poor dentition
• strabismus
• sleep abnormalities including narcolepsy, excessive sleepiness and apnoeas
• hip dysplasia
• short stature, small hands and feet
• lack of sexual maturity