On Monday, scientists attempted to edit a gene within the human body for the very first time in history, in order to permanently change a person's DNA to cure a disease. Brian Madeux, 44, suffers from Hunter Syndrome. The syndrome is a rare genetic disease (less than 10,000 people worldwide) causing a missing or malfunctioning gene that prevents the body from breaking down mucopolysaccharides. The buildup of these complex molecules can lead to a number of symptoms: frequent colds and ear infections, distrorted facial features, hearing loss, heart problems, breathing trouble, skin and eye problems, bone and joint flaws, bowel issues, and developmental delays. Madeux currently needs regular enzyme replacement therapy to break down the mucopolysaccharides, but while the weekly doses help to ease some of the symptoms, it is time-consuming, costly ($100,000 to $400,000 a year), and doesn't prevent brain damage.
The experimental treatment given to Madeux included infusing billions of copies of a corrective gene as well as a genetic tool to cut his DNA in a precise spot into his bloodstream through an IV. The gene editing tool used is called Zinc Finger Nuclease, which involves a virus that has been reprogrammed to find and attach to specific cells, inserting the new gene and two zinc finger proteins. The therapy has been designed so that it becomes active only once it has reached the appropriate destination, which in this case is the liver cells. The hope is that this will fix the kinks in Madeux's genetic code, helping to relieve him of many of the symptoms associated with Hunter Syndrome and prevent him from requiring the necessary weekly enzyme therapy.
Gene editing has been used before, but cells were always removed from the body, edited, checked for errors, and then injected back into the patient. This approach works in many cases where tissue can be temporarily removed and later returned, but it is impossible for organs such as the liver, heart, or brain.
The first results from Madeux's treatment are expected within a month, but the researchers will know for certain if the treatment worked within three months' time. The treatment will not be able to reverse all of the damage in his body, but it is expected to halt the progression of the disease. If this treatment proves successful, it could potentially revolutionize modern medicine, helping to ease the discomforts associated with many different genetic diseases.
Sources:
http://www.iflscience.com/health-and-medicine/scientists-try-in-body-gene-editing-for-the-first-time/
https://www.outerplaces.com/science/item/17091-genes-edit-inside-body
https://apnews.com/4ae98919b52e43d8a8960e0e260feb0a
http://www.bbc.com/news/health-42009929
http://www.theatlantic.com/science/archive/2017/11/sangamo-first-gene-editing-in-body/545960
Friday, November 17, 2017
Friday, November 10, 2017
Next-generation Sequencing in Forensic Science
The Sanger sequencing method was introduced in the 1970's, which led to enormous advances in molecular biology and genetics. However, the method did have several disadvantages, including low throughput, high cost, and operation difficulties. The introduction of next-generation sequencing (NGS) technology has seemingly overcome these issues, and researchers are now working to further develop the technology to apply to various fields. including forensic science.
DNA analysis is an incredibly important tool in forensic science, where in forensic DNA tests today employ PCR and capillary electrophoresis (CE)-based fragment analysis to detect length variations in short tandem repeat (STR) markers. CE-based analysis, though, comes with several limitations, including the inability to analyze multiple genetic polymorphisms in a single reaction using a single workflow, low resolution mtDNA and mixture analysis, and low-resolution genotyping of current markers. NGS technology allows for the ability to sequence millions to billions of DNA molecules in parallel, increasing the throughput and minimizing the need for the fragment-cloning method used in Sanger sequencing. It includes second- and third-generation sequencing technology, which can analyze a large number of samples simultaneously and determine the base composition of single DNA molecules, respectively. The limitations presented by CE-based analysis are therefore pushing researchers to further explore the potential for NGS technology in forensic science.
DNA sequencing is also an important tool in forensic identification, and a number of recent studies have found evidence supporting the idea that epigenetic markers could be used to distinguish monozygotic (MZ) twins, predict tissue type, and accurately determine the age of a DNA donor. It is thought that information within the human genome could provide insight into a person's characteristics such as ethnicity, physical and psychological characteristics, and age. It is a real possibility for next-generation sequencing to be used in the future to infer a criminal suspect's physical, psychological, and geographical characteristics from biological samples collected from crime scenes.
Although NGS seems to have a future in forensic science, it still has a long way to go and several obstacles to overcome, including the generation of guidelines for its application in the field, before we will see it put to use.
Source:
http://www.sciencedirect.com/science/article/pii/S1672022914001053
DNA analysis is an incredibly important tool in forensic science, where in forensic DNA tests today employ PCR and capillary electrophoresis (CE)-based fragment analysis to detect length variations in short tandem repeat (STR) markers. CE-based analysis, though, comes with several limitations, including the inability to analyze multiple genetic polymorphisms in a single reaction using a single workflow, low resolution mtDNA and mixture analysis, and low-resolution genotyping of current markers. NGS technology allows for the ability to sequence millions to billions of DNA molecules in parallel, increasing the throughput and minimizing the need for the fragment-cloning method used in Sanger sequencing. It includes second- and third-generation sequencing technology, which can analyze a large number of samples simultaneously and determine the base composition of single DNA molecules, respectively. The limitations presented by CE-based analysis are therefore pushing researchers to further explore the potential for NGS technology in forensic science.
DNA sequencing is also an important tool in forensic identification, and a number of recent studies have found evidence supporting the idea that epigenetic markers could be used to distinguish monozygotic (MZ) twins, predict tissue type, and accurately determine the age of a DNA donor. It is thought that information within the human genome could provide insight into a person's characteristics such as ethnicity, physical and psychological characteristics, and age. It is a real possibility for next-generation sequencing to be used in the future to infer a criminal suspect's physical, psychological, and geographical characteristics from biological samples collected from crime scenes.
Although NGS seems to have a future in forensic science, it still has a long way to go and several obstacles to overcome, including the generation of guidelines for its application in the field, before we will see it put to use.
Source:
http://www.sciencedirect.com/science/article/pii/S1672022914001053
Friday, October 13, 2017
MiRNA Analysis in Forensic Science
RNA was first introduced into forensic literature in 1984 when post-mortem RNA synthesis was described. It took several more years until another study was conducted introducing gene expression analysis, and even then it wasn't until after crucial advances were made when gene expression analysis was adopted by forensic laboratories and further applications using RNA were explored. When these applications were tested, the potential use for RNA in the identification of body-fluids and wound age estimation was uncovered. Today, body-fluid identification via specific mRNA quantification is an established standard technique in many forensic laboratories.
Even though successful mRNA recovery and profiling from even aged samples has been demonstrated, mRNA stability and susceptibility to degradation has always been an issue for mRNA based gene expression analysis, and impaired mRNA integrity impacts the reproducibility of the results. This was expected to be especially problematic for forensic routine applications using mRNA, because biological stains from casework are often met with challenges such as moisture, UV light, temperature, etc., which would potentially degrade mRNA beyond usability. miRNA profiling has been shown to have potentially serious advantages over mRNA profiling. Due to their small size of about 22 nt, mature miRNAs are much more stable than mRNAs, which makes them decidedly less susceptible against fractionation by chemical or physical strain. MiRNA profiling also has greater discriminatory potential than mRNA profiling, and it is believed that miRNA could even outperform mRNA profiling when it comes to identification of mixed and/or heavily environmentally challenged stains.
Initial studies clearly show the potential of miRNA profiling for forensic science. In a study conducted in 2009, it was demonstrated that miRNA can be extracted from forensic samples. Using blood, saliva, semen, vaginal secretions, and menstrual blood, they created body fluid specific assays consisting of two differentially expressed miRNAs per body fluid which they used to successfully identify and discriminate each. Menstrual blood could clearly be distinguished from non-menstrual blood and even sperm-free semen could reliably be detected.
Although more research is needed before using the analysis in the field, miRNA-profiling may become a very promising tool for forensic analysis
Source:
https://ac.els-cdn.com/S0379073810003312/1-s2.0-S0379073810003312-main.pdf?_tid=df0b85de-
b07b-11e7-9d9a-00000aab0f27&acdnat=1507943352_b92987412bf86dfc27c427e23edccfe2
Even though successful mRNA recovery and profiling from even aged samples has been demonstrated, mRNA stability and susceptibility to degradation has always been an issue for mRNA based gene expression analysis, and impaired mRNA integrity impacts the reproducibility of the results. This was expected to be especially problematic for forensic routine applications using mRNA, because biological stains from casework are often met with challenges such as moisture, UV light, temperature, etc., which would potentially degrade mRNA beyond usability. miRNA profiling has been shown to have potentially serious advantages over mRNA profiling. Due to their small size of about 22 nt, mature miRNAs are much more stable than mRNAs, which makes them decidedly less susceptible against fractionation by chemical or physical strain. MiRNA profiling also has greater discriminatory potential than mRNA profiling, and it is believed that miRNA could even outperform mRNA profiling when it comes to identification of mixed and/or heavily environmentally challenged stains.
Initial studies clearly show the potential of miRNA profiling for forensic science. In a study conducted in 2009, it was demonstrated that miRNA can be extracted from forensic samples. Using blood, saliva, semen, vaginal secretions, and menstrual blood, they created body fluid specific assays consisting of two differentially expressed miRNAs per body fluid which they used to successfully identify and discriminate each. Menstrual blood could clearly be distinguished from non-menstrual blood and even sperm-free semen could reliably be detected.
Although more research is needed before using the analysis in the field, miRNA-profiling may become a very promising tool for forensic analysis
Source:
https://ac.els-cdn.com/S0379073810003312/1-s2.0-S0379073810003312-main.pdf?_tid=df0b85de-
b07b-11e7-9d9a-00000aab0f27&acdnat=1507943352_b92987412bf86dfc27c427e23edccfe2
Friday, October 6, 2017
Hair Analysis in Forensics
Hair analysis was initially used in the 1960s and 1970s to evaluate exposure to toxic heavy metals through the use of atomic absorption spectroscopy. At the time, it was not possible to examine hair for drugs because the methods weren't sensitive enough. Years later, the use of radioimmunoassay allowed for the detection of certain organic drugs in hair. Today, gas chromatography coupled with mass spectrometry is the method of choice and is routinely used to document drug exposure in forensic science. One major advantage of hair testing compared to blood or urine testing is that it has a larger window (weeks to months versus 2 to 4 days) and is therefore able to provide a long-term history of an individual's drug use. Hair samples are typically taken from the scalp, although it has been suggested that other locations, such as arm hair, pubic hair, or axillary hair, could be used for alternative sources of drug detection when scalp hair is not available. While it has been suggested, various studies have found significant differences in drug concentrations between scalp hair and these alternative sources. These differences are believed to be caused by better blood circulation, a greater number of apocrine glands, and a different growth rate.
The mechanism by which the chemicals are bound to hair is not exactly known, although several suggestions have emerged. It was suggested that diffusion enhanced by drug binding to intracellular components of hair cells such as the hair pigment melanin could be a cause. However, this would not be the only mechanism as, when tested, drugs are trapped into the hair of albino animals, which lack melanin. Another proposed mechanism was the possibility of the drug binding with certain sulphydryl-containing amino acids and diffusing into the hair cells. The abundance of amino acids such as cysteine form cross-linking disulfide bonds, which would bind the drugs. Various studies have also demonstrated that when given the same dosage, black hair tends to incorporate a greater amount of the drugs when compared to blond hair. This gives rise to discussions about a possible genetic variability of drug disposition in hair.
Of course, much more research is required before all questions surrounding hair drug testing can be satisfied, but it seems that hair analysis for the identification of drug use is quickly gaining recognition. Hair analysis could be a very useful tool to use in conjunction with conventional drug testing in toxicology.
The mechanism by which the chemicals are bound to hair is not exactly known, although several suggestions have emerged. It was suggested that diffusion enhanced by drug binding to intracellular components of hair cells such as the hair pigment melanin could be a cause. However, this would not be the only mechanism as, when tested, drugs are trapped into the hair of albino animals, which lack melanin. Another proposed mechanism was the possibility of the drug binding with certain sulphydryl-containing amino acids and diffusing into the hair cells. The abundance of amino acids such as cysteine form cross-linking disulfide bonds, which would bind the drugs. Various studies have also demonstrated that when given the same dosage, black hair tends to incorporate a greater amount of the drugs when compared to blond hair. This gives rise to discussions about a possible genetic variability of drug disposition in hair.
Of course, much more research is required before all questions surrounding hair drug testing can be satisfied, but it seems that hair analysis for the identification of drug use is quickly gaining recognition. Hair analysis could be a very useful tool to use in conjunction with conventional drug testing in toxicology.
Friday, September 22, 2017
Gene Therapy for Blood Genetic Diseases
RNAi-based gene therapy (RNA interference) is quickly becoming a hot topic in the world of therapies for blood diseases. Blood diseases are those defined as disorders in the hematopoietic system or plasma compounds. Therapeutic approaches for these diseases are divided into several categories, including chemotherapy, radiotherapy, hematopoietic stem cell transplantation, and RNAi-based gene therapy. Of these, RNAi-based gene therapy is progressively becoming an alternative offering the possibility of a permanent cure for some blood diseases.
Gene therapy attempts to treat inherited diseases using normal copies of the defective genes to correct a cellular dysfunction or provide a new cellular function. RNAi not only suppresses transcription by transcriptional gene silencing but it also activates a homology-based mRNA degradation process by post-transcriptional gene silencing, both of which result in the decrease of the coding transcript level (mRNA).
RNAi-based gene therapy possesses several therapeutic advantages, including less immunogenicity. This is in large part due to using non-protein-coding "gene products" to trigger RNAi, making gene therapy potentially less likely to be hindered by the host immune system. Another potential advantage is sequence specificity, which, when compared to traditional small molecules and protein drugs, in combination with the universal treatment spectrum make it an ideal treatment for blood genetic diseases.
One example of the advantage of RNAi-based gene therapy is seen through research conducted with myeloid leukemia. Many therapies have been explored as a cure for this disease, of which chemotherapy is always considered a frontline treatment, mainly containing cytotoxic agents and therapeutic molecules. Although the leukemia cells initially respond well to chemotherapy, it tends to lose some effectiveness after about 6-12 months. In addition, side effects of traditional cytotoxic agents arise, which limit its function with the progression of the disease. RNAi-based gene therapy has been explored by researchers in suppressing the growth and proliferation of myeloid leukemia cells. The results showed a significant decrease in the level of target proteins by limiting the expression of certain genes. RNAi-based gene therapy, when compared to treatments such as chemotherapy, would have a significant effect on the cells with the potential for a notable decrease in side effects.
Although a very exciting possible form of therapy for these types of diseases, there is much research to be done before determining whether RNAi-based therapeutics would be an efficient tool. It seems though that the therapy, in combination with other therapies, could be a very effective new way to treat blood genetic diseases.
Gene therapy attempts to treat inherited diseases using normal copies of the defective genes to correct a cellular dysfunction or provide a new cellular function. RNAi not only suppresses transcription by transcriptional gene silencing but it also activates a homology-based mRNA degradation process by post-transcriptional gene silencing, both of which result in the decrease of the coding transcript level (mRNA).
RNAi-based gene therapy possesses several therapeutic advantages, including less immunogenicity. This is in large part due to using non-protein-coding "gene products" to trigger RNAi, making gene therapy potentially less likely to be hindered by the host immune system. Another potential advantage is sequence specificity, which, when compared to traditional small molecules and protein drugs, in combination with the universal treatment spectrum make it an ideal treatment for blood genetic diseases.
One example of the advantage of RNAi-based gene therapy is seen through research conducted with myeloid leukemia. Many therapies have been explored as a cure for this disease, of which chemotherapy is always considered a frontline treatment, mainly containing cytotoxic agents and therapeutic molecules. Although the leukemia cells initially respond well to chemotherapy, it tends to lose some effectiveness after about 6-12 months. In addition, side effects of traditional cytotoxic agents arise, which limit its function with the progression of the disease. RNAi-based gene therapy has been explored by researchers in suppressing the growth and proliferation of myeloid leukemia cells. The results showed a significant decrease in the level of target proteins by limiting the expression of certain genes. RNAi-based gene therapy, when compared to treatments such as chemotherapy, would have a significant effect on the cells with the potential for a notable decrease in side effects.
Although a very exciting possible form of therapy for these types of diseases, there is much research to be done before determining whether RNAi-based therapeutics would be an efficient tool. It seems though that the therapy, in combination with other therapies, could be a very effective new way to treat blood genetic diseases.
Friday, September 15, 2017
Genetics in Forensic Odontolgy
Anyone who knows me knows that I am absolutely obsessed with forensics, which is why I decided 10 years ago that I was going to make it my life. I decided that I was going to study forensics in college (even though I hadn't even made it to high school yet), and that I was going to make a career out of it. I typically focus on things dealing with DNA or trace analysis, but I found an interesting article connected with a different branch of forensics: forensic odontology. Forensic odontology, or forensic dentistry, is branch of forensic medicine in which teeth are used in the identification of victims when their bodies are unrecognizable.
Genetic material is obtained in different ways when comparing living suspects to deceased victims. When dealing with living suspects, genetic material is typically obtained through blood or a cheek swab. On the other hand, in order to help determine the identity of a deceased person, the method of obtaining genetic material is a bit more complicated. When it comes to verifying a familial relation involving post-mortem material, time from death and corpse condition play a significant role in the method used. In more recent deaths, soft tissue is a viable option, whereas in situations of longer periods of time, the soft tissue is no longer a suitable option and sources such as bone and teeth are used.
Teeth are a great source of genetic material as natural teeth are the most durable organs in the bodies of vertebrates and they have significant tissue resistance against external injuries. The dental pulp presents a better condition for DNA extraction than other soft tissues as it is protected by the tooth structure. The genetic material extracted from the victim is then compared to either the genetic material obtained from a presumed family member or from a known DNA profile of the victim.
Sources:
http://medind.nic.in/jal/t12/i1/jalt12i1p55.pdf
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3612186/
Genetic material is obtained in different ways when comparing living suspects to deceased victims. When dealing with living suspects, genetic material is typically obtained through blood or a cheek swab. On the other hand, in order to help determine the identity of a deceased person, the method of obtaining genetic material is a bit more complicated. When it comes to verifying a familial relation involving post-mortem material, time from death and corpse condition play a significant role in the method used. In more recent deaths, soft tissue is a viable option, whereas in situations of longer periods of time, the soft tissue is no longer a suitable option and sources such as bone and teeth are used.
Teeth are a great source of genetic material as natural teeth are the most durable organs in the bodies of vertebrates and they have significant tissue resistance against external injuries. The dental pulp presents a better condition for DNA extraction than other soft tissues as it is protected by the tooth structure. The genetic material extracted from the victim is then compared to either the genetic material obtained from a presumed family member or from a known DNA profile of the victim.
Sources:
http://medind.nic.in/jal/t12/i1/jalt12i1p55.pdf
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3612186/
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