Sotos Syndrome

**Semantic type:** Disease or Syndrome

**Definition:** An autosomal dominant overgrowth syndrome caused by mutation(s) of the NSD1 or the NFIX gene, encoding H3 lysine-36 and H4 lysine-20 specific histone-lysine N-methyltransferase, and nuclear factor 1 X-type, respectively. The condition is characterized by a disproportionately large and long head with a slightly prominent forehead and pointed chin, hypertelorism, down-slanting eyes, large hands and feet, overgrowth in childhood, and developmental delay.