SMN1 (Survival of motor neurone 1)

Certainty Style Key

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True   Likely   Speculative
Human Uniqueness Compared to "Great Apes": 
Likely Difference
MOCA Domain: 
MOCA Topic Authors: 

Survival of motor neuron 1 (SMN1) is involved in the assembly of small nuclear ribonucleoproteins (snRNPs), which are important for pre-mRNA splicing. SMN1 loss is associated with spinal muscular atrophy, an autosomal recessive neuromuscular disorder that leads to loss and dysfunction of motor neurons. SMN1 copies are found within a 500kb 15q13 inverted duplication region that is highly prone to rearrangements and deletions. Humans have 1-3 more copies of SMN1 than any other primate, although the significance of these copies is unknown.


Timing of appearance of the difference in the Hominin Lineage as a defined date or a lineage separation event. The point in time associated with lineage separation events may change in the future as the scientific community agrees upon better time estimates. Lineage separation events are defined in 2017 as:

  • the Last Common Ancestor (LCA) of humans and old world monkeys was 25,000 - 30,000 thousand (25 - 30 million) years ago
  • the Last Common Ancestor (LCA) of humans and chimpanzees was 6,000 - 8,000 thousand (6 - 8 million) years ago
  • the emergence of the genus Homo was 2,000 thousand (2 million) years ago
  • the Last Common Ancestor (LCA) of humans and neanderthals was 500 thousand years ago
  • the common ancestor of modern humans was 100 - 300 thousand years ago

Probable Appearance: 
2,000 thousand years ago
Definite Appearance: 
6,000 thousand years ago
Genetics Topic Attributes
Gene symbols follow the HUGO Gene Nomenclature Committee standard.
Gene Symbol Type of Human-Specific Changes
SMN1 Copy Number Changes


  1. Diversity of human copy number variation and multicopy genes., Sudmant, Peter H., Kitzman Jacob O., Antonacci Francesca, Alkan Can, Malig Maika, Tsalenko Anya, Sampas Nick, Bruhn Laurakay, Shendure Jay, and Eichler Evan E. , Science, 10/2010, Volume 330, Issue 6004, p.641-6, (2010)
  2. A population-based study of genotypic and phenotypic variability in children with spinal muscular atrophy., Arkblad, Eva, Tulinius Már, Kroksmark Anna-Karin, Henricsson Mirja, and Darin Niklas , Acta Paediatr, 05/2009, Volume 98, Issue 5, p.865-72, (2009)
  3. Spinal muscular atrophy: why do low levels of survival motor neuron protein make motor neurons sick?, Burghes, Arthur H. M., and Beattie Christine E. , Nat Rev Neurosci, 2009 Aug, Volume 10, Issue 8, p.597-609, (2009)
  4. Lineage-specific gene duplication and loss in human and great ape evolution., Fortna, A., Kim Y., MacLaren E., Marshall K., Hahn G., Meltesen L., Brenton M., Hink R., Burgers S., Hernandez-Boussard T., et al. , PLoS Biol, 07/2004, Volume 2, Issue 7, p.E207, (2004)