Question: Which gene is responsible for the development of Sotos syndrome?

Context:
Sotos syndrome is a well-known overgrowth syndrome characterized by excessive growth during childhood, macrocephaly, distinctive facial appearance and learning disability. This disorder is caused by mutations or deletions in NSD1 gene
Sotos syndrome (SoS) is a multiple anomaly, congenital disorder characterized by overgrowth, macrocephaly, distinctive facial features and variable degree of intellectual disability. Haploinsufficiency of the NSD1 gene at 5q35.3, arising from 5q35 microdeletions, point mutations, and partial gene deletions, accounts for a majority of patients with SoS
Mutations and deletions of the NSD1 gene, located on chromosome 5q35, are responsible for over 90% of cases of Sotos syndrome.
The NSD1 gene was recently found to be responsible for Sotos syndrome, and more than 150 patients with NSD1 alterations have been identified.
Recently, deletions encompassing the nuclear receptor binding SET-Domain 1 (NSD1) gene have been described as the major cause of Japanese patients with the Sotos syndrome, whereas point mutations have been identified in the majority of European Sotos syndrome patients.
Mutations in NSD1 are responsible for Sotos syndrome, but are not a frequent finding in other overgrowth phenotypes.
Spectrum of NSD1 gene mutations in southern Chinese patients with Sotos syndrome.
Two cases of Sotos syndrome with novel mutations of the NSD1 gene.
Mutations and deletions of the NSD1 gene, located on chromosome 5q35, are responsible for over 90% of cases of Sotos syndrome
Haploinsufficiency of the NSD1 gene due to 5q35 microdeletions or intragenic mutations is the major cause of Sotos syndrome characterized by generalized overgrowth, large hands and feet with advanced bone age, craniofacial dysmorphic features, learning disability, and possible susceptibility to tumors
Spectrum of NSD1 gene mutations in southern Chinese patients with Sotos syndrome
Haploinsufficiency of the NSD1 gene has been implicated as the major cause of Sotos syndrome, with a predominance of microdeletions reported in Japanese patients
Haploinsufficiency of the NSD1 gene due to 5q35 microdeletions or intragenic mutations is the major cause of Sotos syndrome characterized by generalized overgrowth, large hands and feet with advanced bone age, craniofacial dysmorphic features, learning disability, and possible susceptibility to tumors. 
Clinical and genetic spectrum of 18 unrelated Korean patients with Sotos syndrome: frequent 5q35 microdeletion and identification of four novel NSD1 mutations.
Craniofacial and oral features of Sotos syndrome: differences in patients with submicroscopic deletion and mutation of NSD1 gene.
Prenatal diagnosis and molecular cytogenetic characterization of a 1.07-Mb microdeletion at 5q35.2-q35.3 associated with NSD1 haploinsufficiency and Sotos syndrome.
Autosomal dominant mutations and deletions of the nuclear receptor set domain gene (NSD1), which is located at chromosome 5q35, are responsible for most of the cases. 
There are two types of mutations that cause NSD1 haploinsufficiency: mutations within the NSD1 gene (mutation type) and a 5q35 submicroscopic deletion encompassing the entire NSD1 gene (deletion type). 
Sotos syndrome is a rare genetic disorder characterized by overgrowth associated with macrocephaly and delayed psychomotor development. Patients with Sotos syndrome show 5q35 deletions involving NSD1 or its point mutations.
Mutations in NSD1 are responsible for Sotos syndrome,
Mutations and deletions of the NSD1 gene, located on chromosome 5q35, are responsible for over 90% of cases of Sotos syndrome.
The NSD1 gene was recently found to be responsible for Sotos syndrome, and more than 150 patients with NSD1 alterations have been identified.
Mutations in NSD1 are responsible for Sotos syndrome, but are not a frequent finding in other overgrowth phenotypes.

Answer: Sotos syndrome (SoS) is a multiple anomaly, congenital disorder characterized by overgrowth, macrocephaly, distinctive facial features and variable degree of intellectual disability. Haploinsufficiency of the NSD1 gene at 5q35.3, arising from 5q35 microdeletions, point mutations, and partial gene deletions, accounts for a majority of patients with SoS.
Sotos syndrome is a well-known overgrowth syndrome characterized by excessive growth during childhood, macrocephaly, distinctive facial appearance and learning disability. This disorder is caused by mutations or deletions in NSD1 gene
Exact answer: NSD1 gene