21 year old Nigerian. German major, Chemistry minor. Premed. Science lover and lover of language. German, virology, epidemiology, nuclear chemistry, orgo you name it!
Aniridia is a genetic condition that affects people at birth. The term “aniridia” literally means “without iris” (the colored part of the eye), which is generally the first indication that an individual has aniridia. A person who has aniridia is born without a fully developed iris. The name ‘aniridia’ is somewhat misleading because aniridia is a panocular condition, meaning it usually affects other components of the anatomy of the eye in addition to the iris.
Actually, the lack of the iris is the least of the ocular problems associated with aniridia. Aniridia can affect the entire anatomy – the cornea, the fovea or retina, as well as the lens. As a result, ocular conditions can include glaucoma, foveal hypoplasia, nystagmus, strabismus, dry eye, corneal degeneration, and cataracts. Most people with aniridia have at least one of these associated ocular conditions that impact their vision.
Aniridia is a rare eye condition, affecting approximately 1 in 60,000 births. However, the ocular problems associated with aniridia mentioned above are quite common. What is rare is to have all of these conditions present in one individual.
Although people with aniridia always have vision problems, the degree varies greatly and is dependent upon which complications, in addition to the lack of iris, an individual has. Generally, individuals with aniridia have a visual acuity measurement between 20/80 and 20/200. Some are legally blind, while others have vision good enough to drive a car. Most individuals with aniridia read without using Braille, especially in today’s technically advanced environment of e-Readers.
It is important to note that some of the conditions related to aniridia are non-degenerative (meaning they do not get worse over time) and others are degenerative. Conditions that can degenerate the vision of an individual with aniridia include corneal keratopathy, glaucoma, and cataracts. For more information on these conditions and treatments, please refer to the menu on the right ‘Aniridia’s Impact on Vision’ under the ‘Learn More’ heading.
Avoiding the transmission of mitochondrial disease takes a trio, but raises a host of logistical issues.
When first used in humans in the 1970s, in-vitro fertilization (IVF) raised significant ethical, legal, and philosophical concerns. The ability to manipulate human reproduction was viewed in many circles as an attack on the traditional family and an odious attempt to assert human dominion over nature. Terms such as “designer babies” and “playing God” were commonly applied to IVF. Nevertheless, much of the scientific community touted the potential benefits of these technologies, viewing them as the start of a new era of medicine. Indeed, despite those dire predictions four decades ago, IVF is now widely accepted and has enabled infertile couples to conceive more than 5 million healthy babies.
Fourteen years ago, my Columbia University colleagues and I (JL) examined the mitochondrial origins of Dolly, the cloned sheep, and proposed the concept of a “three-parent” fertility procedure to treat mitochondrial disorders (Nat Genet, 23:90-93, 1999). The unique genetic information within mitochondria enables these organelles to function as the biochemical engines of the cell. However, sometimes deleterious mutations occur in mitochondrial DNA (mtDNA) that cause myriad human pathologies—such as heart problems, liver failure, brain disorders, blindness, hearing loss, myopathy, and in the most extreme cases, death. These mitochondrial disorders are incurable and are passed down maternally from generation to generation. One in 6,500 children worldwide is affected with mtDNA defects. (See “Power Failure,” The Scientist, May 2011.)
To prevent defective mtDNA from being passed from mother to child, scientists in the U.K. are planning to offer a “three-parent” fertility procedure. Based in part on protocols developed by scientists at the New York Stem Cell Foundation and at Columbia University Medical Center (Nature, 493:632-39, 2013), this procedure modifies standard IVF technology to create an embryo from the eggs of two women and sperm obtained from one man. Specifically, nuclear DNA from the egg of a woman carrying mitochondrial defects is transferred into the enucleated cytoplasm of a donor egg that harbors nonmutated mtDNA. This genetically reconstituted egg is then fertilized in vitro by sperm from a male partner, and the resulting embryo is implanted into the uterus of the woman with the mitochondrial disorder. This embryo will contain genetic material from three donors, but will not express any symptoms of the mitochondrial disorder.
The potential for creating children from multiple parents is not limited to the halting of the passage of mitochondrial disorders. In May 2013, Shoukhrat Mitalipov and his colleagues at the Oregon Health and Science University published a milestone article describing the use of IVF technology to transfer genetic material from any nonsperm cell into a human egg, thereby generating a pre-implantation embryo from which human embryonic stem cells can be readily isolated and maintained in the laboratory (Cell, 153:1228-38, 2013). One of many potential outcomes of this research is the ability to create a human embryo without any male genetic contribution—by transferring the nucleus of a somatic cell from one woman into an enucleated egg of another. Embryos could also be made from more than three genetic parents by merging multiple embryos into a single chimeric infant, as has already been achieved in rhesus monkeys (Cell, 148:285-95, 2012).
Mitochondrial diseases, which are passed down maternally, affect one in 6,500 children worldwide and result from mutations in mitochondrial DNA (mtDNA). They can cause a variety of incurable human pathologies, including heart problems, liver failure, brain disorders, blindness, hearing loss, myopathy and death.
In order to prevent defective mtDNA from being passed to a child, scientists have developed a new procedure that modifies standard in-vitro fertilization (IVF) technology to create an embryo from the eggs of two females, transferring the nuclear DNA from the egg of the female carrying mitochondrial defects into the enucleated cytoplasm of a donor egg that harbors nonmutated mtDNA, and sperm obtained from one male. The resulting embryo is then implanted into the uterus of the woman with the mitochondrial disorder.
IVF itself raised many legal and ethical questions when it first appeared in the 1970s – terms such as “desiglner babies” and “playing God” were thrown around quite liberally – though it has now become widely accepted. This new procedure, however, raises new ones, such as: who are the legal parents of such a child? Would the child have the right to know the identity of all his/her gene donors? And would this just be taking one step closer down the path towards an era of “consumer eugenics”?
News source: http://bit.ly/GzBnVV
Image source: Holding egg. Successful birth of the first frozen oocyte baby in India/OpenI
By reducing the expression of a gene known as mTOR, the scientists extended the average lifespan of a group of mice by around 20%. But the increased lifespan didn’t affect all tissues and organs in the same way - while the mice retained better memory and balance as they aged, their bones deteriorated more quickly than usual.
Read more: http://1.usa.gov/17rdZD5 via NIH
A gene that is associated with regeneration of injured nerve cells has been identified by a team of researchers led by Prof Melissa Rolls of Penn State University.
The team has found that a mutation in a single gene can entirely shut down the process by which axons – the parts of the nerve cell that are responsible for sending signals to other cells – regrow themselves after being cut or damaged.
Meet chimera cat. She recently went viral on the internet - for obvious reasons. Chimera cat is one individual organism, but genetically its own fraternal twin. A chimera is typically formed from four parent cells (either two fertilized eggs, or two early embryos that have fused together). When the organism forms, the cells that had already begun to develop in the separate embryos keep their original phenotypes and appearances. This means that the resulting animal is a mixture of tissues and can look like this gorgeous (but bizarre) kitty.
She also has complete heterochromia, a condition when the eyes are different colours.
Thanks to The Scientist for introducing us to chimera kitty.
DNA Dark Matter Detector Proposed
Performing a DNA test to identify dark matter may seem like something only a seriously mixed-up scientist would do, but a cross-disciplinary group of scientists from the USA say in the very near future that is just what physicists probing the mysteries of the cosmos could be doing. The reason for this is that last week they proposed a new detector for WIMPs (Weakly Interacting Massive Particles), which relies on the properties of DNA. WIMPs are thought to make up the bulk of the mysterious dark mass, needed to explain (among other things) galactic rotation curves and thought to account for 23% of the Universe’s mass-energy (with 72% coming from the equally mysterious dark energy, with visible matter only accounting for the remaining 5%).
The design of the detector is fairly simple: from a very thin sheet of gold foil (approximately 10 atoms thick) are hung evenly-spaced strands of DNA (up to 0.7 micrometers long), with each strand molecularly labeled and placed about 10 nanometers apart. Occasionally a WIMP will hit one of the gold nuclei in the foil, knocking it out of the foil, causing it to smash through the DNA and breaking the strands of DNA. The broken strands are collected on a plate below and techniques from molecular genetics are used to identify where exactly the nucleus severed the DNA strands. The experiment consists of several detectors stacked on top of each other and from this the direction and speed of the WIMP can be worked out.
The main advantage of the novel dark matter detector is its ability to detect the direction of the incoming WIMP, which is important as it helps to distinguish WIMPs from other particles such as cosmic ray photons. Another advantage of the new experiment is that it is much smaller (coming in at only ~1kg) than conventional WIMP detection experiments, which are usually very large and often need to be housed deep underground. The experiment should also be able to probe lower energies than current WIMP detectors are able to. John Davis
ArXiv blog: http://www.technologyreview.com/view/428391/revolutionary-dna-tracking-chamber-could-detect/
Original paper: http://arxiv.org/abs/1206.6809
Geneticists from the Max Planck Institute have fully sequenced the genome of the bonobo ape. Bonobos are (along with chimpanzees) our closest living relatives. They were the last of the extant great apes to have their genome sequenced.
This sequencing has allowed scientists to calculate when they last shared an ancestor with their close cousins, the chimpanzees. This is now estimated to have been about one million years ago, which coincides with the formation of the Congo river which separates the two modern species. It’s possible that it was the formation of this river that created the geographical boundary that led to their speciation.