SIGLEC6 (sialic acid binding Ig-like lectin 6)

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Siglec-6 is a sialic acid recognizing protein expressed in certain immune cell types of all hominids. Surprisingly it is selectively expressed in the human placental trophoblast, but  not un the chimpanzee or gorilla placenta. Mechanistically this may be related to changes in the promoter region, and the significance of the selective expression is unknown. As SIGLEC6 may show increasing expression human labor and following childbirth, it has been speculated that this expression helps to slow the tempo of human labor.  Interestingly, expression of Siglec-6 is further upregulated in pre-eclampsia, which appears to be a uniquely human disease.



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

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Genetics Topic Attributes
Gene symbols follow the HUGO Gene Nomenclature Committee standard.
Gene Symbol Type of Human-Specific Changes
SIGLEC6 Expression Pattern Change


  1. Severe preeclampsia-related changes in gene expression at the maternal-fetal interface include sialic acid-binding immunoglobulin-like lectin-6 and pappalysin-2., Winn, Virginia D., Gormley Matthew, Paquet Agnes C., Kjaer-Sorensen Kasper, Kramer Anita, Rumer Kristen K., Haimov-Kochman Ronit, Yeh Ru-Fang, Overgaard Michael T., Varki Ajit, et al. , Endocrinology, 2009 Jan, Volume 150, Issue 1, p.452-62, (2009)
  2. Human-specific expression of Siglec-6 in the placenta, Van der Linden, E. C. Brinkma, Hurtado-Ziola N., Hayakawa T., Wiggleton L., Benirschke K., Varki Ajit, and Varki Nissi M. , Glycobiology, Sep, Volume 17, Number 9, p.922-31, (2007)