YOUR HEALTH Dr James Le Fanu: 19 April
When recently a friend introduced her delightful three-year-old twin daughters, they were quite obviously non-identical, being very dissimilar in appearance and hair colour – one blonde, the other brunette.
‘Oh, no,’ she commented. ‘They are identical, all right. We even had them tested.’
‘That simply cannot be,’ I responded.
But apparently it can be, for it turns out that one in 10 pairs of genetically identical twins are physically non-identical. This is a new discovery as the relevant tests could not be done until a few years ago – but it has revolutionary implications for our understanding of what genes do.
Genetics is an abstruse science, but the underlying principle is easy enough to grasp. The 20,000 or so genes within each cell form the ‘blueprint’, determining important aspects of who we are: our height, intelligence, the colour of our eyes and hair, susceptibility to diseases and so on. Hence the millions of pounds poured into the Human Genome Project in anticipation that spelling out the genetic code in its entirety would clarify all there is to know about ourselves at this most fundamental level.
Identical twins brought up separately (or ‘reared apart’) have always provided much the strongest evidence for this determinant role of the genes – all the way down to smoking the same brand of cigarettes and marrying wives with the same Christian name.
But those physically nonidentical/ identical twins would seem to undermine the whole project. As the happy outcome of a single fertilised egg that has split in two, they share precisely the same set of genes – so their obvious dissimilarities can only mean that genetic blueprint is less important than was previously thought.
This only illustrates how little we really know. For if our genes can both determine our lives down to the finest detail, yet in other instances fail to determine something as simple as hair colour, clearly their true function is something of a biological mystery.
THIS WEEK’S MEDICAL QUERY comes courtesy of a lady from Reading who, when returning to bed in the middle of the night, develops a headache almost as soon as her head touches the pillow. The pain is particularly focused on her eyes, ‘not always the same one and on one occasion very intense in both’, she writes. What, she wonders, could be the explanation.
These headaches/eye pains are indeed very puzzling but could perhaps be due to pressure on the nerves arising from the vertebrae in the neck, brought on by relaxation of the supportive neck muscles. This is probably associated with ‘wear and tear’ of the neck vertebrae, in which case taking an antiinflammatory drug such as ibuprofen before retiring at night might prevent this happening. Alternatively, there is the option of wearing a neck collar at night. It can be a bit uncomfortable, but might be similarly effective.
drjames@lady.co.uk
‘When I have an incipient boil, I apply saliva and after a couple of days it has gone,’ reports a lady from Middlesex. And a reader from Surbiton says she has found that saliva can help disperse warts: ‘I first discovered this by nibbling at a wart on my finger. For warts outside the nibbling range, wet the tip of the finger to apply.’
‘Oh, no,’ she commented. ‘They are identical, all right. We even had them tested.’
‘That simply cannot be,’ I responded.
But apparently it can be, for it turns out that one in 10 pairs of genetically identical twins are physically non-identical. This is a new discovery as the relevant tests could not be done until a few years ago – but it has revolutionary implications for our understanding of what genes do.
Genetics is an abstruse science, but the underlying principle is easy enough to grasp. The 20,000 or so genes within each cell form the ‘blueprint’, determining important aspects of who we are: our height, intelligence, the colour of our eyes and hair, susceptibility to diseases and so on. Hence the millions of pounds poured into the Human Genome Project in anticipation that spelling out the genetic code in its entirety would clarify all there is to know about ourselves at this most fundamental level.
Identical twins brought up separately (or ‘reared apart’) have always provided much the strongest evidence for this determinant role of the genes – all the way down to smoking the same brand of cigarettes and marrying wives with the same Christian name.
But those physically nonidentical/ identical twins would seem to undermine the whole project. As the happy outcome of a single fertilised egg that has split in two, they share precisely the same set of genes – so their obvious dissimilarities can only mean that genetic blueprint is less important than was previously thought.
This only illustrates how little we really know. For if our genes can both determine our lives down to the finest detail, yet in other instances fail to determine something as simple as hair colour, clearly their true function is something of a biological mystery.
THIS WEEK’S MEDICAL QUERY comes courtesy of a lady from Reading who, when returning to bed in the middle of the night, develops a headache almost as soon as her head touches the pillow. The pain is particularly focused on her eyes, ‘not always the same one and on one occasion very intense in both’, she writes. What, she wonders, could be the explanation.
These headaches/eye pains are indeed very puzzling but could perhaps be due to pressure on the nerves arising from the vertebrae in the neck, brought on by relaxation of the supportive neck muscles. This is probably associated with ‘wear and tear’ of the neck vertebrae, in which case taking an antiinflammatory drug such as ibuprofen before retiring at night might prevent this happening. Alternatively, there is the option of wearing a neck collar at night. It can be a bit uncomfortable, but might be similarly effective.
drjames@lady.co.uk
Licking her wounds
Saliva contains compounds hostile to the growth of bacteria, of which several have been identified – including lysozyme, which attacks cell walls, and lactoferrin, which mops up the iron they need to grow. Hence the value of saliva in preventing infections such as boils.‘When I have an incipient boil, I apply saliva and after a couple of days it has gone,’ reports a lady from Middlesex. And a reader from Surbiton says she has found that saliva can help disperse warts: ‘I first discovered this by nibbling at a wart on my finger. For warts outside the nibbling range, wet the tip of the finger to apply.’