Human accelerated regions (HARs), first described in August 2006, are a set of 49 segments of the

human genome The human genome is a complete set of nucleic acid sequences for humans, encoded as DNA within the 23 chromosome pairs in cell nuclei and in a small DNA molecule found within individual mitochondria. These are usually treated separately as the ...

that are conserved throughout

vertebrate Vertebrates () comprise all animal taxon, taxa within the subphylum Vertebrata () (chordates with vertebral column, backbones), including all mammals, birds, reptiles, amphibians, and fish. Vertebrates represent the overwhelming majority of the ...

evolution but are strikingly different in

human Humans (''Homo sapiens'') are the most abundant and widespread species of primate, characterized by bipedalism and exceptional cognitive skills due to a large and complex brain. This has enabled the development of advanced tools, culture, ...

s. They are named according to their degree of difference between humans and chimpanzees (HAR1 showing the largest degree of human-chimpanzee differences). Found by scanning through genomic databases of multiple species, some of these highly

mutated In biology, a mutation is an alteration in the nucleic acid sequence of the genome of an organism, virus, or extrachromosomal DNA. Viral genomes contain either DNA or RNA. Mutations result from errors during DNA or viral replication, mitos ...

areas may contribute to human-specific traits. Others may represent loss of functional mutations, possibly due to the action of biased

gene conversion Gene conversion is the process by which one DNA sequence replaces a homologous sequence such that the sequences become identical after the conversion event. Gene conversion can be either allelic, meaning that one allele of the same gene replaces ...

rather than adaptive evolution. Details of HAR1–HAR5 journal

Several of the HARs encompass genes known to produce proteins important in neurodevelopment. HAR1 is a 106-base pair stretch found on the long arm of

chromosome 20 Chromosome 20 is one of the 23 pairs of chromosomes in humans. Chromosome 20 spans around 66 million base pairs (the building material of DNA) and represents between 2 and 2.5 percent of the total DNA in cells. Chromosome 20 was fully sequenced ...

overlapping with part of the RNA genes HAR1F and HAR1R. HAR1F is active in the developing human brain. The HAR1 sequence is found (and conserved) in chickens and chimpanzees but is not present in fish or frogs that have been studied. There are 18 base pair mutations different between humans and chimpanzees, far more than expected by its history of conservation.supplement
/ref> HAR2 includes HACNS1 a gene enhancer "that may have contributed to the evolution of the uniquely opposable human

thumb The thumb is the first digit of the hand, next to the index finger. When a person is standing in the medical anatomical position (where the palm is facing to the front), the thumb is the outermost digit. The Medical Latin English noun for thu ...

, and possibly also modifications in the

ankle The ankle, or the talocrural region, or the jumping bone (informal) is the area where the foot and the leg meet. The ankle includes three joints: the ankle joint proper or talocrural joint, the subtalar joint, and the inferior tibiofibular ...

or foot that allow humans to walk on two legs". Evidence to date shows that of the 110,000 gene enhancer sequences identified in the human

genome In the fields of molecular biology and genetics, a genome is all the genetic information of an organism. It consists of nucleotide sequences of DNA (or RNA in RNA viruses). The nuclear genome includes protein-coding genes and non-coding ...

, HACNS1 has undergone the most change during the

evolution Evolution is change in the heritable characteristics of biological populations over successive generations. These characteristics are the expressions of genes, which are passed on from parent to offspring during reproduction. Variation ...

of humans following the split with the ancestors of chimpanzees. The substitutions in HAR2 may have resulted in loss of binding sites for a repressor, possibly due to biased gene conversion.

HAR-associated genes

* HAR01: HAR1F & HAR1R *HAR02: CENTG2 including HACNS1 *HAR03: MAD1L1 *HAR04: *HAR05:

WNK1 WNK (lysine deficient protein kinase 1), also known as WNK1, is an enzyme that is encoded by the ''WNK1'' gene. WNK1 is serine-threonine protein kinase and part of the "with no lysine/K" kinase WNK family. The predominant role of WNK1 is the regu ...

*HAR06:

WWOX WW domain-containing oxidoreductase is an enzyme that in humans is encoded by the ''WWOX'' gene In biology, the word gene (from , ; "... Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''gener ...

*HAR07: *HAR08: POU6F2 *HAR09: PTPRT *HAR10: FHIT *HAR11:

DMD DMD may refer to: Science and medicine * Dimethyldioxirane, an organic molecule * Doctor of Dental Medicine, an academic degree for the profession of Dentistry * Duchenne muscular dystrophy, a neurodegenerative disease * Dysmyelogenic leukod ...

*HAR12: EBF *HAR20: PPARGC1A *HAR21: NPAS3 - association with psychiatric disorders *HAR23:

MGC27016 MGC can refer to: * Machine Gun Corps * Malvern Girls College * Massachusetts General Court, legislature of that U.S. state * Media Gateway Controller, a device in Voice over IP networks * Medical Grade Cannabis * Megestrol caproate, a proges ...

*HAR24:

SCAP2 SCAP may refer to: * S.C.A.P., an early French manufacturer of cars and engines * Security Content Automation Protocol * '' The Shackled City Adventure Path'', a role-playing game * SREBP cleavage activating protein * Supervisory Capital Assessm ...

*HAR28: LPHN4 *HAR31:

AUTS2 AUTS2, activator of transcription and developmental regulator is a protein that in humans is encoded by the AUTS2 gene. Function This gene has been implicated in neurodevelopment and as a candidate gene for numerous neurological disorders, in ...

*HAR33: TBC1D22A *HAR38: ITPR1 *HAR40: ZBTB16 *HAR43: AGBL4 *HAR44: FHIT *HAR45: POLA *HAR47: KLHL14

References

{{reflist Molecular genetics Human genetics Human evolution

HAR-associated genes

See also

References