News & views
Since the last time we ran this course – three months ago - we have been tracking the appearance of genomics in the news in order to assess how salient it is in the ever changing news cycle.
It has surprised even us how frequently genomics news stories appear. Almost daily we hear about the impact of genomics on healthcare and how gene-directed diagnosis and therapies are transforming our understanding of widely divergent fields of medicine. We thought we would share with you some of the stories we found particularly interesting. They exemplify the extent to which genomics is going to change everyone’s lives, whether as a patient or as a healthcare professional.
Three parent babies
The first baby with three parents could be born this year. At the beginning of December it was announced that the Human Fertilisation and Embryology Authority (HFEA) has given the green light to a revolutionary technique known as mitochondrial replacement therapy (MRT). MRT is used for women who are known carriers for, frequently devastating, mitochondrial disorders. Mitochondria are the powerhouses of the cells and contain a set of DNA that is distinct and separate from the nuclear DNA. A baby’s mitochondria are inherited exclusively from the mother and so mitochondrial disorders are inherited through the maternal line.
With the announcement that MRT is legal, clinics are now able to offer couples the option of using donor eggs: the mother’s nucleus replaces that of the donor egg and then in vitro fertilisation takes place. Although this is likely to transform the outcome for couples where there is an inherited mitochondrial disorder, there has also been concern expressed by some that we are tampering with nature. If you are interested in these debates you will have the opportunity to explore them at greater depth in the last week of the course.
Silent killers: genes that cause sudden cardiac death
Many of you will have read the news stories surrounding James Taylor, the former England and Nottinghamshire batsman who was forced to retire at the age of 25 having been diagnosed with AVRC (Arrhythmogenic Arrhythmogenic Right Ventricular Cardiomyopathy), an inherited cardiac condition.
These stories often make the headlines and leave us feeling shocked but usually comforted by the thought that “it will never happen to me”. But a recent study, supported by the British Heart Foundation suggests that more than 620 000 people in the UK are likely to have a faulty gene that puts them at risk of heart disease; and most of the carriers for these faulty genes are completely unaware of it. But it’s not all bad news. As our knowledge of these causative genes grows and testing becomes more accessible to everyone, there is a much greater chance that people at risk will be diagnosed early and be able to access appropriate treatment and surveillance. In week four we’ll consider some more about testing for cardiac disease.
Human-pig Chimeras: an extraordinary scientific advance or a travesty of nature?
In Greek mythology, the chimera was a fire breathing monster predominantly lion but with the head of a goat arising from his back and the tail of a serpent. In modern biology, a chimera refers to an organism comprised of more than one genetically different tissue, fused in early embryonic development.
Scientists from the Salk institute in California, have recently reported that they have developed a pig-human chimera. They introduced human stem cells into an early pig embryo that was then reimplanted into the sow. Out of 2,000 reimplanted hybrids, about 150 developed into chimeras, predominantly comprised of pig cells with a small proportion of human cells (about one in 10,000).
The pig-human chimera has been hailed as transformational for modern transplant medicine: the hope is that human organs could be grown and harvested from the chimeras. However, the study has also raised huge ethical concerns centred around “intelligent animals” and interference with nature. Study lead, Juan Carlos Izpisua Belmonte, is reported to have said “The idea of having an animal being born composing of human cells creates some feelings that need to be addressed.” What do you think? We will be thinking about some of the ethics surrounding genomics in the final week of this course. Please do feel free to share your thoughts with your fellow learners.
Gene editing as targeted gene therapy
Since the development of the CRISPR/Cas9 gene-editing tool, there has been intense speculation about its potential use for gene therapy (i.e. the replacement of a faulty gene with a working copy), for a variety of genetic diseases.
A major barrier to this was that gene editing only worked efficiently in dividing cells, not in mature, non-dividing adult tissues. Now, a study published in Nature, and reported in The Guardian in November, has described an adapted gene editing system which is able to edit genes in both dividing and non-dividing cells in vitro and, most importantly, mature cells in vivo.
The researchers, based at the Salk Institute in California, used a rat model of the genetic disease, retinitis pigmentosa, which causes blindness in about 1 in 4000 people, and for which there is currently no cure. They used a virus to deliver the gene-editing package to the rats, and were able to demonstrate evidence of healing in their retinal cells and improved vision.
This study provides proof of principle of the use of gene editing for somatic gene therapy. Now the focus will be on ensuring the safety and efficacy of the technology. These are by no means insignificant issues, and clinical trials may yet be a way off, however this development could open the door for the development of treatments for a range of devastating and currently incurable genetic diseases.
A TAD interesting…
A news story in the New York Times in January of this year discussed a fascinating case, where a single family with a genetic condition opened up a new mechanism for disease causation. TADS or Toplogically Associated Domains are areas of the genome where sections of the genetic code can be read through physical interactions of different parts of the DNA strand when folded in a particular 3D structure, instead of in the normal linear way.
Imagine a piece of string lying on a table with letters written upon it. When the string is lying flat, the letters can be read along it in either direction in a linear fashion. However, if you tied a knot in the string, the new configuration of the string would place letters previously spaced far apart from each other, in close proximity, secondary to this structural change. This could allow you to read the letters across the 3 dimensional fold of the knot, instead of in a one dimensional linear way. Have a read and see what you think about this new disease causing mechanism.
From a patient’s perspective
Whilst scouring the media for genomic news, we came across this article written by an author with cystic fibrosis. Reading this gives some human insight into the impact of genomics on the individual and may put the hard science of this week into some perspective!
Which of these stories interests you most and why? Have any other stories about genomics in the press caught your eye?
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