SIGLEC1 (sialic acid binding Ig-like lectin 1, sialoadhesin)

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Siglec-1/Sialoadhesin is a conserved sialic acid recognizing protein that is expressed in subsets of rodent and primate macrophages. As it does not bind well to the non-human sialic acid Neu5Gc, humans have an increased density of ligands for this molecule. Human Sialoadhesin show enhanced expression and a wider distribution in splenic macrophages, in comparison to chimpanzees. Further studies are needed to ascertain if this expression difference is due to changes in the promoter region of this gene or due to other systemic factors. Sialoadhesin is capable of mediating phagocytosis of pathogens than express the sialic acid Neu5Ac (the precursor of Neu5Gc, which accumulates in humans), and humans are prone to infections by such pathogens.  Thus, the wider distribution of Sialoadhesin in human spleen may reflect an evolutionary response to the selection pressure of these pathogens.



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

Possible Appearance (Lineage Separation Event): 
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Genetics Topic Attributes
Gene symbols follow the HUGO Gene Nomenclature Committee standard.
Gene Symbol Type of Human-Specific Changes
SIGLEC1 Expression Pattern Change


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