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The official name of this gene is “son of sevenless homolog 1 (Drosophila).”
SOS1 is the gene's official symbol. The SOS1 gene is also known by other names, listed below.
The SOS1 gene provides instructions for making a protein that is involved in pathways within cells that control growth and development. This protein helps control (regulate) the activation of the RAS/MAPK signaling pathway, which helps control several important cell functions. Specifically, it regulates the growth and division of cells (proliferation), the process by which cells mature to carry out specific functions (differentiation), cell movement, and the self-destruction of cells (apoptosis). The SOS1 protein regulates another protein, called Ras, that stimulates cells to grow and divide. This regulation tightly controls the growth of cells and tissues, and is especially important for proper embryonic development.
The SOS1 gene belongs to a family of genes called ARHGEF (Rho guanine nucleotide exchange factors).
A gene family is a group of genes that share important characteristics. Classifying individual genes into families helps researchers describe how genes are related to each other. For more information, see What are gene families? (http://ghr.nlm.nih.gov/handbook/howgeneswork/genefamilies) in the Handbook.
More than 20 mutations causing Noonan syndrome have been identified in the SOS1 gene. These mutations change single protein building blocks (amino acids) in the SOS1 protein. The resulting protein is continuously active, rather than switching on and off in response to other cellular proteins. This increase in protein activity disrupts the regulation of the RAS/MAPK signaling pathway that controls cell functions such as growth and division. This misregulation can result in the heart defects, growth problems, skeletal abnormalities, and other features of Noonan syndrome.
Mutations in the SOS1 gene can also cause hereditary gingival fibromatosis type 1. This disorder is characterized by a slowly progressive overgrowth of the tissue of the gums (gingiva). Too much of this tissue can impair teeth from emerging through the gums, which can cause difficulties in speech and chewing food. At least one mutation in the SOS1 gene has been shown to cause hereditary gingival fibromatosis type 1. This mutation is an addition of a single building block of DNA (nucleotide). The mutation inserts the nucleotide cytosine into an area of the gene called exon 21 (written 3248_3249insC) and disrupts the gene's instructions, resulting a shortened protein. Unlike the normal SOS1 protein, the shortened protein is permanently active because it is missing areas that regulate its activity. Instead of triggering cell growth in response to particular signals from outside the cell, the overactive protein directs cells to grow and divide constantly. It is unclear why the overgrowth of tissue is seen only in the gums.
Cytogenetic Location: 2p21
Molecular Location on chromosome 2: base pairs 39,208,689 to 39,347,685
The SOS1 gene is located on the short (p) arm of chromosome 2 at position 21.
More precisely, the SOS1 gene is located from base pair 39,208,689 to base pair 39,347,685 on chromosome 2.
See How do geneticists indicate the location of a gene? (http://ghr.nlm.nih.gov/handbook/howgeneswork/genelocation) in the Handbook.
You and your healthcare professional may find the following resources about SOS1 helpful.
You may also be interested in these resources, which are designed for genetics professionals and researchers.
See How are genetic conditions and genes named? (http://ghr.nlm.nih.gov/handbook/mutationsanddisorders/naming) in the Handbook.
acids ; apoptosis ; cell ; cytosine ; differentiation ; DNA ; embryonic ; exon ; gene ; gingiva ; gingival ; gums ; mutation ; nucleotide ; proliferation ; protein ; RAS ; syndrome ; tissue
You may find definitions for these and many other terms in the Genetics Home Reference Glossary (http://www.ghr.nlm.nih.gov/glossary).
The resources on this site should not be used as a substitute for professional medical care or advice. Users seeking information about a personal genetic disease, syndrome, or condition should consult with a qualified healthcare professional. See How can I find a genetics professional in my area? (http://ghr.nlm.nih.gov/handbook/consult/findingprofessional) in the Handbook.