Sotos syndrome is a congenital overgrowth syndrome that affects approximately 1 in 14,000 of the population. It was first recognised as a syndrome in 1964. Initial research often used the terms ‘cerebral gigantism’ and ‘Sotos syndrome’ interchangeably to refer to the same condition, due to the large head circumference that is associated with the syndrome. However, cerebral gigantism is no longer considered appropriate and therefore the condition is now only referred to as Sotos syndrome.
The following features are typically used to establish an initial, clinical diagnosis:
- Characteristic facial appearance
- Learning disability
- Childhood overgrowth
- Increased head circumference
In approximately ninety percent of cases, the clinical diagnosis is confirmed using a genetic test to detect an abnormality on the NSD1 gene. Some individuals may be diagnosed at birth but many others do not receive a diagnosis until well into childhood.
Medical problems that can affect children with Sotos syndrome include:
- Congenital heart and kidney defects
- Scoliosis (curvature of the spine)
- Persistent infections of the urinary and respiratory tracts
Sotos Syndrome is an autosomal dominant condition which means that if either one of the parents has Sotos, there is a fifty percent chance that each of their children will inherit the condition. The chance of a couple having a second child with Sotos syndrome is the same as for any other couple (approximately one in fourteen thousand) provided they do not have the syndrome themselves.
Children with tall stature, i.e. above the 99.6th centile, are usually so because of genetic reasons – they simply have tall parents! This is referred to as constitutional tall stature. However, tall stature may also be associated with various paediatric syndromes that require specialist assessment. Two of these conditions are Marfan syndrome and Sotos syndrome.
Constitutional tall stature
Tall stature in childhood usually presents less initial concern than short stature because, at least in early childhood, being tall can be advantageous. However, excessive tall stature can cause problems, particularly at school. It may be difficult to remember that a five-year old child who has the stature of an eight-year-old only has the educational and emotional development of a five-year old. Their size can seem inappropriate for their classroom peers and so very tall children may be labelled as clumsy or aggressive.
Typical growth chart for Sotos Syndrome