HASAsts

HASaSTs, or human accelerated regions of segmentally duplicated and tandemly arrayed sequences in tandem, are a class of human gene families that have been accelerated in their evolutionary rate. These genes are found in regions of the genome known as human accelerated regions (HARs), which have undergone rapid evolution over the past 5-10 million years.

Studies have shown that HASaSTs are repeat families that are duplicated and diverged in tandem, often producing gene pairs that are highly similar but not identical. These genes often have roles in cellular processes such as cell growth and developmental pathways. The human and chimpanzee genomes show extensive differences in the sequence, microsatellite sizes, and fragment length polymorphism of these regions, which have been replicated in a series of insertions of each kind.

The evolutionary mechanisms behind the rapid expansion of HASaSTs are not yet fully understood. However, studies suggest that positive selection, gene duplication, and gene amplification have contributed to the diversification of these gene families. HASaSTs represent a minor fraction of the human genome, but the gene families have significantly expanded in humans relative to chimpanzees.

Research on HASaSTs has implicated these gene families in the evolutionary changes that have occurred in human beings. They have been linked to human-specific coelacanth genomic duplications, suggesting that HASaSTs might be involved in the evolution of novel genes and gene functions in humans. HASaSTs have been described as key players in human evolutionary history, particularly during the period of rapid brain expansion. The continued study of HASaSTs will provide further insights into the complex factors contributing to human evolution.

In a wider genomic context, HASaSTs have become a prominent focus as prime candidates for study, given their co-occurrence with signatures of positive selection, intense gene duplication, and amplification, pointing towards a dissection of their intricate, lineage-specific evolutionary origins.