Microcephalin: Difference between revisions
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included one of the news links (the other's a duplicate) as a lay summary. i'll be more careful not to delete them next time |
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==Evolution== |
==Evolution== |
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A derived form of ''MCPH1'' called [[haplogroup]] D appeared about 37,000 years ago (anytime between 14,000 and 60,000 years ago) and has spread to become the more common form throughout the world except [[Sub-Saharan Africa]] |
A derived form of ''MCPH1'' called [[haplogroup]] D appeared about 37,000 years ago (anytime between 14,000 and 60,000 years ago) and has spread to become the more common form throughout the world except [[Sub-Saharan Africa]]. It is therefore very possible that the timing of its emergence narrowly preceded the [[Upper Paleolithic]], when people started colonising Europe.<ref> |
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{{cite journal |
{{cite journal |
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| author = Evans, P.D., ''et al.'' |
| author = Evans, P.D., ''et al.'' |
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| year = 2005 |
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| title = ''Microcephalin'', a gene regulating brain size, continues to evolve adaptively in humans |
| title = ''Microcephalin'', a gene regulating brain size, continues to evolve adaptively in humans |
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| journal = [[Science (journal)|Science]] |
| journal = [[Science (journal)|Science]] |
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| volume = 309 |
| volume = 309 |
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| pages = 1717-20 |
| pages = 1717-20 |
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| ⚫ | |||
| accessdate = 2007-06-21 |
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| laysummary = http://www.nytimes.com/2005/09/08/science/08cnd-brain.html?ex=1283832000&en=631902c8dabfb269&ei=5090&partner=rssuserland&emc=rss |
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| ⚫ | |||
| laysource = New York Times: Researchers Say Human Brain Is Still Evolving}} |
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</ref> The distribution of [[chromosome]]s bearing the ancestral forms of ''MCPH1'' and ''[[ASPM|MCPH5]]'' coincide with the incidence of [[tonal language]]s, although the exact nature of the relationship is unknown.<ref> |
</ref> The distribution of [[chromosome]]s bearing the ancestral forms of ''MCPH1'' and ''[[ASPM|MCPH5]]'' coincide with the incidence of [[tonal language]]s, although the exact nature of the relationship is unknown.<ref> |
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{{cite journal |
{{cite journal |
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Revision as of 16:45, 1 July 2007
| microcephaly, primary autosomal recessive 1 | |||||||
|---|---|---|---|---|---|---|---|
| Identifiers | |||||||
| Symbol | MCPH1 | ||||||
| NCBI gene | 79648 | ||||||
| HGNC | 6954 | ||||||
| OMIM | 607117 | ||||||
| UniProt | Q8NEM0 | ||||||
| Other data | |||||||
| Locus | Chr. 8 p23 | ||||||
| |||||||
| microcephaly, primary autosomal recessive 2 | |
|---|---|
| Identifiers | |
| Symbol | MCPH2 |
| NCBI gene | 4181 |
| HGNC | 6955 |
| OMIM | 604317 |
| Other data | |
| Locus | Chr. 19 q13.1-13.2 |
| microcephaly, primary autosomal recessive 3 | |
|---|---|
| Identifiers | |
| Symbol | MCPH3 |
| Alt. symbols | CDK5RAP2 |
| NCBI gene | 23702 |
| HGNC | 6956 |
| OMIM | 604804 |
| Other data | |
| Locus | Chr. 9 q33.3 |
| microcephaly, primary autosomal recessive 4 | |
|---|---|
| Identifiers | |
| Symbol | MCPH4 |
| NCBI gene | 23701 |
| HGNC | 6957 |
| OMIM | 604321 |
| Other data | |
| Locus | Chr. 15 q15-21 |
| microcephaly, primary autosomal recessive 5 | |
|---|---|
| Identifiers | |
| Symbol | MCPH5 |
| Alt. symbols | ASPM |
| NCBI gene | 64590 |
| HGNC | 6958 |
| OMIM | 608716 |
| Other data | |
| Locus | Chr. 1 q31 |
| microcephaly, primary autosomal recessive 6 | |
|---|---|
| Identifiers | |
| Symbol | MCPH6 |
| Alt. symbols | CENPJ |
| NCBI gene | 170629 |
| HGNC | 17120 |
| OMIM | 608393 |
| Other data | |
| Locus | Chr. 13 q12.2 |
The microcephalins (Greek for "small head) are a group of genes associated with brain development.[1][2] It is named after the loss-of-function mutations in any of the six genes in the group (called MCPH1 to MCPH6), which cause microcephaly (Online Mendelian Inheritance in Man (OMIM): 251200), a condition characterised by a severely diminished brain.[3][4]
Evolution
A derived form of MCPH1 called haplogroup D appeared about 37,000 years ago (anytime between 14,000 and 60,000 years ago) and has spread to become the more common form throughout the world except Sub-Saharan Africa. It is therefore very possible that the timing of its emergence narrowly preceded the Upper Paleolithic, when people started colonising Europe.[5] The distribution of chromosomes bearing the ancestral forms of MCPH1 and MCPH5 coincide with the incidence of tonal languages, although the exact nature of the relationship is unknown.[6]
Haplogroup D may have originated from a lineage separated from modern humans approximately 1.1 million years ago and later introgressed into humans. This finding supports the possibility of admixture between modern humans and extinct Homo spp. (Neanderthals being one possibility).[7] On the other hand the sample of 89 individuals with only 9 Africans used in the study has been criticized as being inadequate for the conclusion the paper draws, and comparable studies demostrate that undersampling specific areas of East/Central Africa may lead to unwarranted conclusions.[8]
Expression in the brain
MCPH1 is expressed in the fetal brain, in the developing forebrain, and on the walls of the lateral ventricles. Cells of this area divide, producing neurons that migrate to eventually form the cerebral cortex.
Other names
The microcephaly-related genes MCPH 3, 5 and 6 are usually classified by their alternate names CDK5RAP2, ASPM and CENPJ respectively, according to their other roles. More information can be found from the articles dedicated to them and links in the information boxes.
Sources and notes
- ^ Wang, Y.Q. & B. Su (2004). "Molecular evolution of microcephalin, a gene determining human brain size". Hum. Mol. Genet. 13: 1131–1137. doi:10.1093/hmg/ddh127.
- ^
Evans, P.D.; et al. (2004). "Reconstructing the evolutionary history of microcephalin, a gene controlling human brain size". Hum. Mol. Genet. 13: 1139–1145. doi:10.1093/hmg/ddh126.
{{cite journal}}: Explicit use of et al. in:|author=(help) - ^
Jackson, A.P.; et al. (1998). "Primary Autosomal Recessive Microcephaly (MCPH1) Maps to Chromosome 8p22-pter". Am. J. Hum. Genet. 63: 541–546. PMID 9683597.
{{cite journal}}: Explicit use of et al. in:|author=(help) - ^
Jackson, A.P.; et al. (2002). "Identification of Microcephalin, a Protein Implicated in Determining the Size of the Human Brain". Am. J. Hum. Genet. 71: 136–142. PMID 12046007.
{{cite journal}}: Explicit use of et al. in:|author=(help) - ^
Evans, P.D.; et al. (2005). "Microcephalin, a gene regulating brain size, continues to evolve adaptively in humans". Science. 309: 1717–20. doi:10.1126/science.1113722.
{{cite journal}}: Explicit use of et al. in:|author=(help); Unknown parameter|laysource=ignored (help); Unknown parameter|laysummary=ignored (help) - ^ Dediu, D. & D.R. Ladd (2007). "Linguistic tone is related to the population frequency of the adaptive haplogroups of two brain size genes, ASPM and Microcephalin". Proc. Nat. Acad. Sci. doi:10.1073/pnas.0610848104.
- ^ PNAS article Evidence that the adaptive allele of the brain size gene microcephalin introgressed into Homo sapiens from an archaic Homo lineage Published online before print November 7, 2006 by Proceedings of the National Academy of Sciences of the USA
- ^ Shimada MK, Panchapakesan K, Tishkoff SA, Nato AQ, Hey J (2007). "Divergent haplotypes and human history as revealed in a worldwide survey of X-linked DNA sequence variation". Mol. Biol. Evol. 24 (3): 687–98. doi:10.1093/molbev/msl196. PMID 17175528.
{{cite journal}}: CS1 maint: multiple names: authors list (link)
External links
- Neanderthal Brains - a lecture by Bruce Lahn - from the NYAS podcasts.