Sotos syndrome: History
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Sotos syndrome is a disorder characterized by a distinctive facial appearance, overgrowth in childhood, and learning disabilities or delayed development of mental and movement abilities. Characteristic facial features include a long, narrow face; a high forehead; flushed (reddened) cheeks; and a small, pointed chin. In addition, the outside corners of the eyes may point downward (down-slanting palpebral fissures). This facial appearance is most notable in early childhood. Affected infants and children tend to grow quickly; they are significantly taller than their siblings and peers and have an unusually large head. However, adult height is usually in the normal range.

  • genetic conditions

Frequency

Sotos syndrome is reported to occur in 1 in 10,000 to 14,000 newborns. Because many of the features of Sotos syndrome can be attributed to other conditions, many cases of this disorder are likely not properly diagnosed, so the true incidence may be closer to 1 in 5,000.

Causes

Mutations in the NSD1 gene are the primary cause of Sotos syndrome, accounting for up to 90 percent of cases. Other genetic causes of this condition have not been identified.

The NSD1 gene provides instructions for making a protein that functions as a histone methyltransferase. Histone methyltransferases are enzymes that modify structural proteins called histones, which attach (bind) to DNA and give chromosomes their shape. By adding a molecule called a methyl group to histones (a process called methylation), histone methyltransferases regulate the activity of certain genes and can turn them on and off as needed. The NSD1 protein controls the activity of genes involved in normal growth and development, although most of these genes have not been identified.

Genetic changes involving the NSD1 gene prevent one copy of the gene from producing any functional protein. Research suggests that a reduced amount of NSD1 protein disrupts the normal activity of genes involved in growth and development. However, it remains unclear exactly how a shortage of this protein during development leads to overgrowth, learning disabilities, and the other features of Sotos syndrome.

Inheritance

About 95 percent of Sotos syndrome cases occur in people with no history of the disorder in their family. Most of these cases result from new mutations involving the NSD1 gene.

A few families have been described with more than one affected family member. These cases helped researchers determine that Sotos syndrome has an autosomal dominant pattern of inheritance. Autosomal dominant inheritance means one copy of the altered gene in each cell is sufficient to cause the disorder.

Other Names for This Condition

  • cerebral gigantism
  • Sotos sequence
  • Sotos' syndrome

This entry is adapted from the peer-reviewed paper https://medlineplus.gov/genetics/condition/sotos-syndrome

References

  1. Ball LJ, Sullivan MD, Dulany S, Stading K, Schaefer GB. Speech-languagecharacteristics of children with Sotos syndrome. Am J Med Genet A. 2005 Aug1;136A(4):363-7.
  2. Cecconi M, Forzano F, Milani D, Cavani S, Baldo C, Selicorni A, Pantaleoni C, Silengo M, Ferrero GB, Scarano G, Della Monica M, Fischetto R, Grammatico P,Majore S, Zampino G, Memo L, Cordisco EL, Neri G, Pierluigi M, Bricarelli FD,Grasso M, Faravelli F. Mutation analysis of the NSD1 gene in a group of 59patients with congenital overgrowth. Am J Med Genet A. 2005 Apr 30;134(3):247-53.
  3. Faravelli F. NSD1 mutations in Sotos syndrome. Am J Med Genet C Semin MedGenet. 2005 Aug 15;137C(1):24-31. Review.
  4. Lapunzina P. Risk of tumorigenesis in overgrowth syndromes: a comprehensivereview. Am J Med Genet C Semin Med Genet. 2005 Aug 15;137C(1):53-71. Review.
  5. Lucio-Eterovic AK, Singh MM, Gardner JE, Veerappan CS, Rice JC, Carpenter PB. Role for the nuclear receptor-binding SET domain protein 1 (NSD1)methyltransferase in coordinating lysine 36 methylation at histone 3 with RNApolymerase II function. Proc Natl Acad Sci U S A. 2010 Sep 28;107(39):16952-7.doi: 10.1073/pnas.1002653107.
  6. Niikawa N. Molecular basis of Sotos syndrome. Horm Res. 2004;62 Suppl 3:60-5. Review.
  7. Pasillas MP, Shah M, Kamps MP. NSD1 PHD domains bind methylated H3K4 and H3K9 using interactions disrupted by point mutations in human sotos syndrome. HumMutat. 2011 Mar;32(3):292-8. doi: 10.1002/humu.21424.
  8. Tatton-Brown K, Cole TRP, Rahman N. Sotos Syndrome. 2004 Dec 17 [updated 2019 Aug 1]. In: Adam MP, Ardinger HH, Pagon RA, Wallace SE, Bean LJH, Stephens K,Amemiya A, editors. GeneReviews® [Internet]. Seattle (WA): University ofWashington, Seattle; 1993-2020. Available fromhttp://www.ncbi.nlm.nih.gov/books/NBK1479/
  9. Tatton-Brown K, Douglas J, Coleman K, Baujat G, Cole TR, Das S, Horn D, HughesHE, Temple IK, Faravelli F, Waggoner D, Turkmen S, Cormier-Daire V, Irrthum A,Rahman N; Childhood Overgrowth Collaboration. Genotype-phenotype associations in Sotos syndrome: an analysis of 266 individuals with NSD1 aberrations. Am J HumGenet. 2005 Aug;77(2):193-204.
  10. Tatton-Brown K, Rahman N. Clinical features of NSD1-positive Sotos syndrome.Clin Dysmorphol. 2004 Oct;13(4):199-204.
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