What can gene research do for conditions such as Down’s syndrome?
Somebody with Down’s has an extra copy of chromosome 21, so has 47 chromosomes in total, instead of the usual 46. This means that all of the genes on that chromosome are present in three copies instead of the usual two. The idea that a doctor could remove the extra chromosome is difficult to imagine at present, as every one of the 100 trillion cells in that person’s body has that extra chromosome. Maybe the strategy is to focus on the effects on the brain. Somewhere in the collection of genes on chromosome 21 must be some that are very sensitive to ‘dosage’. If we knew which genes were involved, we might be able to devise a drug that would dampen down their production, or compensate for the overdose they create. Treatment would have to start in the early days of brain development. So there may come a time when we could make the consequences of Down’s milder or even reverse them. But that’s a long way off.
