Prader-Willi syndrome is a genetic condition caused by loss of function of genes in the 15q11–q13 region of the paternally inherited copy of chromosome 15. This can be due to a deletion of this portion of the chromosome, or when both copies of chromosome 15 are inherited from the mother.
Features
Key features of Prader-Willi include:
- Hypotonia (poor muscle tone) in infancy
- Hyperphagia (insatiable hunger) later in childhood, leading to obesity
- Mild to moderate learning disability
- Hypopigmentation, with fair skin and hair
- Narrow forehead
- Bitemporal narrowing (reduced distance between the temples)
- Almond-shaped eyes
- Strabismus (squint)
- Thin upper lip
- Downturned mouth
- Short stature
- Small hands
- Hypogonadism
- Mental health problems (e.g., anxiety and compulsive behaviours)
TOM TIP: The memorable feature of Prader-Willi syndrome is insatiable hunger. However, as an infant, feeding can be a challenge due to hypotonia, leading to failure to thrive. It is only later in childhood that food seeking and excessive eating occur.
Management
Management is supportive with input from the multidisciplinary team. Dieticians play an important role.
Nasogastric feeding may be required early in life, due to hypotonia, poor suck and difficulty feeding.
Hyperphagia (insatiable hunger) means that access to food needs to be carefully limited, under the guidance of a dietician. They may require lower-than-normal calorie intake due to reduced muscle mass and energy expenditure. Limiting access may involve locking food in cupboards, putting a lock on the fridge and even preventing access to bins. Everyone involved in their care needs to be aware of the restrictions on food access.
Growth hormone may be used to improve final adult height, motor development, muscle development and body composition.
Last updated December 2025
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