SIGLEC13 (sialic acid binding Ig-like lectin 13)

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True   Likely   Speculative
Human Uniqueness Compared to "Great Apes": 
Absolute Difference
Human Universality: 
Individual Universal (All Individuals Everywhere)
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The gene for Siglec-13 was specifically deleted in humans by an Alu-mediated recombination event. The protein Siglec-13 is expressed on chimpanzee monocytes, innate immune cells that react to bacteria. Chimpanzee Siglec-13 recruits the DAP12 signaling adapter and bind sialic acids. Expression in innate immune cells alters inflammatory cytokine secretion in response to Toll-like receptor-4 stimulation. The ancestral Siglec-13 is shown to also be engaged by two potentially lethal sialylated bacterial pathogens of newborns and infants, agents with a likely impact on reproductive fitness. Neanderthal and Denisovan genomes show human-like sequences, corroborating estimates that the initial pseudogenization event occurred in the common ancestral population of these species. Sequences flanking the SIGLEC13 deletion in humans also show limited polymorphic diversity, suggesting the there were selection forces closely predating the origin of modern humans. Taken together, the data suggest that genetic elimination of Siglec-13 represents a signature of infectious and/or other inflammatory processes that may have contributed to population restrictions during hominin origins.

 

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Genetics Topic Attributes
Timing

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): 
Probable Appearance (Lineage Separation Event): 
Definite Appearance (Lineage Separation Event): 

References

  1. Specific inactivation of two immunomodulatory SIGLEC genes during human evolution., Wang, Xiaoxia, Mitra Nivedita, Secundino Ismael, Banda Kalyan, Cruz Pedro, Padler-Karavani Vered, Verhagen Andrea, Reid Chris, Lari Martina, Rizzi Ermanno, et al. , Proc Natl Acad Sci U S A, 2012 Jun 19, Volume 109, Issue 25, p.9935-40, (2012)