StemCell Therapy

What is a genome

A genome is a collective term for all the genetic material within an organism. In essence,the genome decides exactly what that organism will look and act like at birth one huge, expansive instruction manual that tellscells their duties. Every living thing has a genome, from bacteria to plants to humans, and they are all different in size with various combinations of genes inside.

The human genome packs in 30,000 genes, but this is just 1% of the total genetic material contained within. Quite frankly, its a mess in there much of the genetic material is duplicated DNA that (supposedly) does very little, and the vast majority of DNA simply doesnt code for anything(these sections are calledintrons). That isnt to say it does nothing. In fact,recent studieshave shown us that non-coding DNA is essential to controlling whether our genes get switched on or not. However, most of the time its the actual genes that are the important bit.

Studying the genome of humans and other organisms is vitalfor a number of reasons.Firstly, it helps us characterize each one before genomics, scientists simply grouped animals and plants by what they looked like, but research into their genes now allows for accuratecharacterization oforganismsinto specificgeneraand species.

In humans, genomic research has allowed researchers to understand the underlying causes of many complex diseases and find possible targets for treatment.Currently, the best tool to do thisisgenome-wide association studies (GWAS).

The idea behind GWAS is relatively intuitive simply take a group of people with the disease you wish to study, and compare their genomesfor common genetic variants that could predict the presence of that disease.These studies have illuminated a huge number of variants linked with higher disease prevalence while also helping researchers to understand the role each gene playsin the human body.Although powerful, GWAS studies are purely a starting point. Following a large-scale GWAS, researchers must thenanalyzeany variants that are highlighted in great depth, and many times such research will provide nothing of clinical relevance. However, itsstill our best way of identifying risk variants in genetic disease.

So,we know the genome is packed to the brim with genes that code for proteins, separated by large strings ofnon-coding DNA. However, when cells replicateearly in development they usually go throughchromosomal recombination, in which chromosomes trade regions of their genetic code between each other. This spreads genes to many different positions (called loci)throughout the genome. If we can make a map of these genes, we candiscover their function, how they are inherited, or target them with therapies.

Therefore, we want to create a genome map.There are two types of maps used in genomics: genetic maps and physical maps.

Physical mapsare relatively straightforward, in which genomic loci are mapped based on the physical distance between them, measured in base pairs.The most common way to create a physical map of a human genome is byfirst breaking the DNA sequence into many fragments, before using a variety of different techniques to identify how those pieces fit back together. By understanding which pieces overlapand reconstructing the shattered genome, scientists can gain a decently accurate map of where each gene lies.

Genetic mapsare slightly different,using specific marker regions within the DNA that are used as trackers. These mapsrequiresamples (usually saliva) from family members,which are then compared toidentifyhow much recombination has occurred that includes markers of interest. The principle is thatif two genes are close together on thechromosome, thenthey are more likely to travel together through the genome as it recombines. By using this data,scientists can get a rough idea of where specific genes lie on chromosomes. However, it is not as accurate as physical mapping andrelies heavilyon a decentpopulation size andthe number of genetic markers used.

A genome browser is any available database that allows a user to access and compare genomes in an intuitive way. When you map or sequence a genome, the data is prettymessy.Genomes are usually stored in huge files, calledFASTAfiles, that contain extensive strings of letters that would look foreign to most users. Genome browsers take this data and make it accessibleto scientists around the globe.

Many genome browsers are available online, containing bacterial, model organism, and human reference genomes.

Genomelinkis one of the latest examples of public access and analysis of genomes. The industry took off in recentyears, with the rapid rise of sites that provide ancestry and medical information based on genomic sequencing, includingAncestryand23andMe.These sites work by comparing genetic markers associated with different populations should you share specific regions of DNA that correspond with African populations, for example, you may have some relation to African ancestors. Each site uses its own markers, so information may vary between tests, and some have disputed the true accuracy of these tests, although advances in genomics have significantly improved them in recent years.

Genomelinkgoes further than most sites, claiming to provide information on a huge variety of genetic traits that a user may have. These include metabolism, sports performance, and even personality traits such as loneliness. Each trait isdrawn from genome correlation studies, with each taking a specific trait and comparing the genomes of each carrier of that trait.

However, although bothGenomelinkand other sites use up-to-date reference genomes and are usually relatively accurate, they should never be substituted for medical information. If you believe you carry a pathogenic genevariant, you should seek advice from a genomic counselor.

Originally posted here:
Genomes, Maps, And How They Affect You - IFLScience

This entry was posted on February 1, 2021 at 4:50 pm and is filed under Genetic medicine. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed. |