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The first ‘map’ of the human genome has been reported by researchers
in Paris – an achievement that should accelerate the hunt for genes linked
to disease and speed international efforts to decode the genome’s vast library
of DNA.

Mapping carves this library into a jigsaw of manageable DNA fragments,
each crudely analogous to a book whose shelf mark has been identified. In
the French map, the DNA fragments, 33 000 in all, are handled in ‘megaYACs’,
artificial chromosomes that can store up to one million base pairs of DNA.
The human genome consists of some 3 billion base pairs spread out over 24
different chromosomes.

The report, in last week’s Nature, comes from Daniel Cohen and his colleagues
at CEPH, the French centre for genetic research, in Paris, and Genethon,
a laboratory funded by tele-thon appeals by the French Muscular Dystrophy
Charity, AFM. Cohen, a staunch critic of attempts to patent human DNA, says
his team’s findings are available to other geneticists through electronic
mail.

The researchers stress their map contains many gaps and is only a first
step towards something more detailed. One unresolved snag with megaYACs
is that they often result in pieces of DNA being ‘shuffled’ into the wrong
place.