Medical Definition of Sotos syndrome

Reviewed on 6/3/2021

Sotos syndrome: a genetic condition that leads to a characteristic facial appearance (long, narrow face, reddened cheeks, high forehead, small chin) as well as delayed mental and motor development or learning disabilities. Overgrowth during childhood is another feature of Sotos syndrome. Other possible symptoms and signs can include:

  • behavioral disturbances,
  • intellectual disability,
  • scoliosis,
  • seizures,
  • heart defects,
  • kidney defects,
  • weak muscle tone,
  • stuttering, or
  • other speech and language problems.

Sotos syndrome has been described as occurring in 1 out of 10,000 to 14,000 newborns. Its features are variable, so it can be confused with other conditions and misdiagnosed. Most cases of Sotos syndrome involve mutations of a gene known as NSD1. In most cases (about 95%) there is no family history of the condition, and the mutation occurs spontaneously rather than being inherited from a parent.

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US National Library of Medicine, Genetics Home Reference. Sotos syndrome. <>