Diving into the gene pool : a user's guide to the new genetic medicine / words, Gail Vines.

  • Vines, Gail.
Date:
1995
Catalogue details

Licence: Attribution 4.0 International (CC BY 4.0)

Credit: Diving into the gene pool : a user's guide to the new genetic medicine / words, Gail Vines. Source: Wellcome Collection.

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    WHEN ISA GENE 'BAD'? Humans have 99.98 per cent of their genetic material in common, but minute genetic variations persist. Many genes exist in the human gene pool in scores or even hundreds of variants, each only slightly different from the next in its sequence of chemical building blocks. Most of the time we are oblivious of such trivial differences. They matter only when they happen to lead to disease. Researchers have now tracked a few hundred, mostly very rare, inherited diseases to single genes. In most cases, a disease actually develops only if an individual inherits two copies of the same faulty gene variant, one from each parent. Some of the more common conditions - such as cystic fibrosis, thalassaemia and sickle cell disease - are inherited in this way. Geneticists call this recessive inheritance. A child has a 1 in 4 chance of being born with the disease if both parents are healthy carriers. The parents have just one copy of the disease gene and suffer no ill effects from it. But in some genetic diseases, inheriting just one copy of a particular gene is enough to cause the full-blown disease. These are the dominant genetic disorders, such as Huntington's disease - which is characterised by a gradual loss of control over movement and mental deterioration in middle age. Each child has a one in two chance of having inherited the disease from a parent who has the Huntington's gene, and who will also eventually develop the disease. Serious genetic diseases can also result from a genetic mishap during the formation of the sperm or egg. About a third of the children born with Duchenne muscular dystrophy fall into this camp. For reasons that are still unclear, some genes seem particularly prone to these spontaneous changes, or mutations. Genes ALSO play an important role in the development of the major killers in the West. The so-called chronic diseases of coronary heart disease, stroke, diabetes and most forms of cancer take years to develop, and are heavily influenced by an individual's diet, body weight, smoking habits and penchant for exercise. But perhaps as many as a dozen genes may also influence our susceptibility to each of these diseases. Most of us know an Uncle Fred who led a dissolute life and lived to a ripe old age, while Aunty Mabel, who did all the right things, was struck down in mid-life. Some of this patent unfairness could well be the result of good or bad luck in the genetic lottery.