recombination process - how genetic info is passed on to offspring

June 1, 2004

How we pass our genes to our children News-Medical.net 1-Jun-2004

An Oxford-led team of researchers has found out more about what happens

during recombination, the process by which the genetic information you

inherited from your mother and father is mixed up to make a sex

chromosome to pass on to your offspring.

The process of recombination occurs when an individual's chromosomes

line up and swap bits of genetic information. In every cell of your body

except the sex cells (sperm and eggs), chromosomes exist in pairs, one

chromosome of the pair from your father, the other from your mother. At

the point when sex cells are made, the chromosomes you inherited from

your father and mother line up and exchange pieces of DNA, recombining

into a totally new chromosome. This new chromosome gets passed on to

your children.

Very few fine details have been known in humans about where these

recombinations were likely to occur, and whether there are many

recombination 'hotspots': points along the DNA where the two lined-up

chromosomes are more likely to exchange genetic information. The

research, published in Science, uses sophisticated new statistical

methods to produce a much more detailed picture than has previously been

available of this variation, and to find many new hotspots.

Dr Gil McVean, Dr Simon Myers, and Professor Donnelly from the

Department of Statistics, and their colleagues from the Sanger

Institute, near Cambridge, have found that 50% of all recombination

events take place in less than 10% of the DNA sequence. They have also

discovered that recombination occurs preferentially outside of genes.

'These findings are interesting for a number of reasons,' said Professor

Donnelly. 'They shed a new light on the process of human recombination,

about which we currently understand rather little. Knowing about

recombination is also very helpful in studies to locate the genes whose

mutations cause diseases. The higher the recombination rate at a

particular point on the genome, the greater the variation there is

likely to be at that point, and disease studies will need to examine

these areas more closely.'

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