The stuff of life is DNA. A simple four letter code written by chemicals that work like a book. Read a DNA chapter and instead of your favourite sonnet, a brain cell is produced or a blue eye. When it works, DNA makes a human being from a single cell, when it malfunctions it leads to diseases like sickle cell disease and cancer. Scientists have long desired the ability to edit DNA to cut out genetic disease ranging from childhood leukaemia to early onset Alzheimer’s.
The problem is that editing genes in a fully grown adult is tricky business. Attempts to perform gene therapy on humans either did not work or had very serious side effects. The solution could be in sight with the breakthrough of the year for 2015: CRISPR.
The CRISPR process was first discovered in bacteria in 2007 by a yoghurt company. By 2013 scientists adopted it. The technology quickly became a science superstar. Bacteria use it to cut out foreign viral DNA that have infected them and integrated their viral DNA within their own. The bacteria can identify the outsiders DNA, chop it out and break it down, inactivating the virus and saving the day. In humans similar viruses lead to diseases like AIDS or cervical cancer.
The technology is so useful to researchers because they can delete, replace, or edit DNA easily and cheaply using a modified bacterial protein coupled to a sequence that guides the mechanism to a specific DNA sequence. Researchers can study a gene by modifying it any way they like and then seeing what happens. Another thing they can do is repair DNA that isn’t working properly which can cure disease.
The technique has already been used to edit human embryonic DNA. The discovery rocked headlines around the world with visions of a master race taking over. Eugenics is a real problem and using DNA editing technology to select for physical human traits will be hard to justify ethically.
DNA editing for medical reasons is a much greyer area since the easiest approach for a geneticist wanting to cure horrible diseases like spinal muscular atrophy (a deadly childhood disease) would be to modify the necessary DNA sequences in the embryo and cure it forever – ethicists disagree.
CRISPR has already been used to edit out the HIV virus from infected cells that saved that cell and protected nearby unedited cells. Other scientists used a modified form of this technology to treat Duchenne muscular dystrophy and leukaemia. The technology has opened a Pandora’s Box, yet it stands to finally develop treatments to safely mitigate a gamut of disease.
Did you know…
• All whales and dolphins (cetaceans) descended from small land-dwelling shrew-like animals.
• The coldest temperature ever recorded on earth is 89.2˚C (-128.6˚F), recorded at Vostok Station, Antarctica, on July 21, 1983.
• There is enough DNA in an average person’s body to stretch from the sun to Pluto and back 17 times.
• The first virus was found in both plants and animals 100 years ago.
For more trivia: www.um.edu.mt/think
Sound bites
• Do not throw away your antibiotics. Trace concentrations are enough to select for antibiotic resistant bacteria, University of York researchers have found. The concentrations are similar to those detected in sewage outflows. These concentrations are much lower than previously thought, and help to explain persistence of antibiotic resistance in the environment.
www.sciencedaily.com/releases/2016/03/160315090336.htm
• Think your DNA is all human? Think again. The human genome might have less human DNA than previously thought due to a new scientific discovery. Nineteen new pieces of non-human DNA – left by viruses that first infected our ancestors hundreds of thousands of years ago – have just been found, hiding between our own genes. The viruses could have been responsible for epidemics or diseases like cancer.
www.sciencedaily.com/releases/2016/03/160322100714.htm