Genome Mapping:  The Future of Medicine

All of the information needed to build a human can be found in its genome.  99.9% of the human genome is the same for everyone.  It is a tenth of a percent that makes everyone different, from what color of hair someone has to a child being born with down syndrome.  In fact, the human genome contains over three billion letters of DNA, called nucleotides.  The sequence of the letters of DNA, (A,T,C,G), are read as a code, and is what makes you, you.  In an effort to identify and understand the function of new genes, genetic mapping was developed.  The mapping of a genome can show where and how a disease that has been passed between a parent to a child is linked to one or more genes.  Human genome mapping should be considered the future of medicine as it is an amazing tool for scientists to use when diagnosing and treating patients.

                                                                                       Source: http://circos.ca/intro/genomic_data/img/circos-conde-nast-large.png

Figure 1:  A Circos image illustrating the human genome.  This particular genome map shows location of genes implicated in disease, those with structural variation and regions of self-similarity within populations.

In order to map a genome, blood and tissue samples are needed from an individual.  If a disease is thought to be hereditarily passed from generation to generation, blood and tissue samples will be taken from multiple family members.  Scientists then use these samples to isolate DNA from them and search for unique sequences, known as DNA markers, that are only found in the individuals that have the disease.  Figure 1 gives an example of the human genome and where common DNA markers can be found.  DNA markers can show approximately where a gene is located on the chromosome.  The more DNA markers that are found on a genome map increases the chances that at least one DNA marker will be close to a disease gene, allowing scientists to focus on that gene.  For more in depth information about genetic sequencing and DNA markers, look at:  https://www.genome.gov/10000715/genetic-mapping-fact-sheet/ .  A good visual for how genome mapping works can be found: https://www.dnalc.org/view/15477-The-public-Human-Genome-Project-mapping-the-genome-sequencing-and-reassembly-3D-animation-.html.

Source: https://thednafiles.wordpress.com/2008/04/17/cystic-fibrosis-and-gene-therapy/

Figure 2:  The CFTR gene found of Chromosome 7 is shown. 

For example, through genetic mapping, researchers were able to isolate which gene causes cystic fibrosis.  As shown in figure 2, the a mutation in the CFTR gene found on chromosome 7 is the source of cystic fibrosis.

Since genome sequencing is still fairly new, not very many healthy individuals are currently having their genome tested.  Some researchers are against mass sequencing of genomes, stating it is not necessary.  One reason for this is the cost of gene sequencing, which averages around $2,900 for every A, T, C, and G to be sequenced.  Another reason some scientists are weary of genome sequencing is the lack of usefulness to many individuals on a personal level.  Upon their genome being sequenced, most healthy individuals will receive no data that is of use to them.  This is leading scientists to debate if it is worth sequencing a lot of people to find the few that could have a genetic mutation leading to disease.  Once those few with genetic mutations are found, it is still not proven that you can treat them and help improve their outcome.

Genomic sequencing can help in many ways.  There are many new techniques and treatments continuously being discovered, and with the early diagnosis that genome mapping can provide many people can benefit from it.  For example, once the mutated or defective gene is found through genome sequencing, it can be treated with a fairly new treatment called gene therapy.  This allows DNA containing a functioning gene of the mutated one to be introduced into a patient.  For more information about gene therapy, look at https://ghr.nlm.nih.gov/primer/therapy/genetherapy.  In the future, more will be known about genome mapping and what the results mean.  This will allow doctors and scientists to create medical advances that we can’t yet imagine.  Until then, the best way for scientists to discover and understand the complexity of the human body is through continuing to research genetics through many means, including genome mapping.