Skip to 0 minutes and 10 seconds Next, the whole exome seq also known as exome seq or WES, is a technology for sequence order, protein coding genes in the genome and known as the exome. It consists of first selection of only the subset of the DNA that encode the protein known as exons and then sequence that DNA use a high throughput DNA sequence technologies. There are 180,000 exons which constitute about 1% of the human genome but mutation in this sequence are much more likely to have a severe consequence than the remaining of the 99%. The goal of this approach is to identify genetic variation that is responsible for common disease such as Miller syndrome, Alzheimer disease without high cost associated with the whole genome sequence.
Skip to 1 minute and 7 seconds The whole exome sequence is especially effective in the study of rare disease because it is the the most efficient way to identify the genetic variance in all of an individual’s gene. This disease are most often caused by a very rare genetic variation that are only present in a tiny number of individuals. By contrast, technology such as SMB arrays can only detect shared genetic variance that are common to many individuals in a wide population. Furthermore, because severe disease cause variance that are much more likely to be in the protein coding sequence, focus on this 1% cost less than whole genome sequence but still produce a high yield of the relevant variance.
Skip to 2 minutes and 2 seconds In the past, clinical genetic test were chosen based on the clinical presentation of the patients or survey only certain types of variations but provide definitive genetic diagnosis in fewer than half of the all patients. Exome seq is now increased use in complement these are the test both to fight the mutation in genes already known to cause the disease as well as to identify the novel genes by comparing axome from the patient with similar features.
Skip to 2 minutes and 40 seconds Finally, we will talk about the genome wide association study of GWAs that are relatively new to analyze the genetic sequence and have a quick become a fundamental part of the modern genetics studies. The purpose of..is to determine that correlate to a different disease and trait. Although the cost of the whole genome sequencing is dropping dramatically recently, it is usually still too expensive to consider sequence a large number of genome required to observe a trend indicating a disease associated with a particular location in the genome. Instead, GWAs focus on SNP, the single nucleotide that differ in between individual. By study SNP researchers has analyzed a few hundred thousand nucleotide whether than 3 billion nucleotide that compose the whole human genome.
Skip to 3 minutes and 39 seconds The basic design of GWAs is simple and begin by individual participants divide into the two groups. First is the people with the disease group. Second is the people without the disease group or we call the control group. The SNP of both groups are analyzed and compared. Researchers hope to identify a particular SNPs present in the disease group that is not present in the control group. If such SNP or SNPS are located, then the researcher have identified the genetic sequence that has association with a particular disease. By collecting the ever-increase amount of the DNA sequence data today, research are able to see if more people are following this trend and in certain allele that correlate with certain diseases.
Skip to 4 minutes and 35 seconds Today, thousands of diseases and traits have been investigated by GWAs including the Type II Diabetes, Pigmentations, Epilepsy, Body mass index, Alzheimer disease, Autism, breast cancer, athma, and High Cholesterol. GWAs are the best of the most direct to consumer genetic companies.
Skip to 5 minutes and 1 second When drawing a conclusion from the GWAs, it is important to recognize that the relationship of identification of the SNP to a particular disease is only association. The most study, it remained unclear how and why a particular SNP has a relationship to disease or trait. Consequently, some people will have a risk variance of allele that is not have a disease and while the other has a with the same disease but without a particular variations. By identification of these specific genes variance, could help us in the future, specific gene therapy and develop high efficient targeting therapies. Thank you very much for today’s talk.
New technologies to identify gene mutations
In the second part of this section, Prof. Sun will explain more of two new technologies to identify human gene mutations:
- Whole exome seq (WES)
- Genome wide association studies (GWAS)
Somatic mosaicism refers to the occurrence of two genetically distinct populations of cells within an individual, derived from a postzygotic mutation.
After watching the videos, please look at the article (link attached below). It outlines the strengths and weaknesses of these techniques and highlights recent insights into the role of somatic mosaicism in causing cancer, neurodegenerative, monogenic, and complex disease. We will discuss some issues next.