Both terms refer to one organism with two or more distinct populations of cells * – but they are not interchangeable. The different cell lines in chimeras originally come from different zygotes whereas mosaics arise from the same zygote. Because mosaics start with the same genome, you expect them to be more similar than chimeras […]
In humans, males are 46XY and females are 46XX. The Y chromosome has been in the news recently but we’re more concerned about the X chromosome today. You’ll notice that there are two copies of the X in human females – do we have double the X gene products? No, X inactivation silences most but […]
One of the hallmarks of medical genetics is non-directive counselling. Therefore, I was dismayed to read the case for selective paternalism in genetic testing in Wired’s Neuron Culture. In most cases, genetic tests only provide information and patients need to determine if they want the information and/or what to do with it. Genetic counsellors should […]
There are lots of new terms at the start of medical school but two terms – penetrance and expressivity – seem to cause undue stress and confusion. One of the first areas of learning for the students is genetics, hopefully because it is central to understanding everything. Is the confusion due to being overwhelmed, strange […]
We see the DNA helix everywhere. It helps market computers, trucks, and cosmetics. People use the helix as an explanation (‘in my DNA’). But do people understand this famous molecule? In different classrooms, I have asked, “If I left DNA from a wolf in a test tube alone in a classroom, what would you do?” Some students […]
I love analogies and use them often to get people to think about scientific concepts in new ways. I’ll share some of my favourite ones on the blog but today, I want to talk about ANALOGIES GONE BAD!
Well, it has happened again. Someone has confused the concept of heritability. A recent Slate article discusses the difficulties of twin studies but screws up the concept of heritability in the first paragraph, saying that genes determine 50% of the likelihood that you will vote among other things. I’ll leave others to critique the rest […]