ASPM (Gene)

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Abnormal spindle-like, microcephaly associated gene
Identifiers
Symbol ASPM
Alt. Symbols MCPH5
Entrez 259266
HUGO 19048
OMIM 605481
RefSeq NM_018136
UniProt Q8IZT6
Other data
Locus Chr. 1 q31

ASPM is a human gene whose defective forms are associated with autosomal recessive primary microcephaly. A new allele (version) of ASPM appeared about 5,800 years ago and has spread to half the world's population, especially Europe and West Asia.

"ASPM" is an acronym for "Abnormal Spindle-like, Microcephaly-associated", which reflects its being an ortholog to the Drosophila melanogaster "abnormal spindle" (asp) gene. ASPM is located on chromosome 1, band q31 (1q31).

The mouse gene, Aspm, is expressed in the primary sites of prenatal cerebral cortical neurogenesis. The difference between Aspm and ASPM is a single, large insertion coding for so-called IQ domains.[1]

Contents

[edit] Role in speech

According to recent research regarding human evolution and cultural development, the most recent ASPM allele arose about 5,800 years ago, roughly correlating with the development of written language, spread of agriculture and development of cities.[1] Currently, two alleles of this gene exist: the older (pre-5,800 years ago) and the newer (post-5,800 years ago). About 10% of humans have two copies of the new ASPM allele, while about 50% have two copies of the old allele. The other 40% of humans have one copy of each. Of those with an instance of the new allele, 50% of them are an identical copy [2] suggesting a highly rapid spread from the original mutation. According to a hypothesis called a "selective sweep", the rapid spread of a mutation (such as the new ASPM) through the population indicates that the mutation is somehow advantageous to the individual.[3] As of today, there is no evidence to support the notion that the new ASPM allele increases intelligence, and some researchers dispute whether the spread of the allele even demonstrates selection[2] [3] [4][5]. However, statistical analysis has shown that the older forms of the gene are found more heavily in populations that speak tonal languages like Chinese.[4]

[edit] Diversity

Instead of ASPM, the DAB1 gene, which also increases the density of neural matter, appears to have come under selection in the Chinese.[5]

[edit] References

  1. ^ Per the 2006 Discovery Channel/Channel 4 documentary series What Makes Us Human?
  2. ^ Woods, R.P., et al. (2006). "Normal variants of Microcephalin and ASPM do not account for brain size variability". Hum. Mol. Genet. 15 (12): 2025-2029. doi:10.1093/hmg/ddl126. 
  3. ^ Mekel-Bobrov, N., et al. (2007). "The ongoing adaptive evolution of ASPM and Microcephalin is not explained by increased intelligence". Hum. Mol. Genet. 16: 600. doi:10.1093/hmg/ddl487. 
  4. ^ New Scientist article
  5. ^ New York Times article

[edit] Notes

  1. ^  An IQ domain is a segment of DNA that codes for the IQ motif.
    IQ protein motif: [FILV]Qxxx[RK]Gxxx[RK]xx[FILVWY]
    The term "IQ" refers to the first two amino acids of the motif: isoleucine (commonly) and glutamine (invariably).
  2. ^  Nitzan Mekel-Bobrov et al. (2005). "Ongoing Adaptive Evolution of ASPM, a Brain Size Determinant in Homo sapiens". Science 309 (5741): 1720–1722. doi:10.1126/science.1116815. 
  3. ^  Mathias Currat et al. (2006). "Comment on "Ongoing Adaptive Evolution of ASPM, a Brain Size Determinant in Homo sapiens"". Science 313 (5784): 172. 
  4. ^  following is one of a large number of similar news articles:
    Study Suggests Human Brains Still Evolving. Live Science: Human Biology. Retrieved on November 26, 2005.
  5. Kniffin, Cassandra L. et al.. ABNORMAL SPINDLE-LIKE, MICROCEPHALY-ASSOCIATED; ASPM. OMIM at the NCBI. Retrieved on August 6, 2005.
    Bruce Lahn moving on to non-IQ projects?. Live Science: Human Biology. Retrieved on June 16, 2006.