What was the ‘draft sequence’ of the Human Genome Project? 

This part 9 in our series of stories about the Human Genome Project. Read part 8, looking at how a race to the finish line led to this draft sequence being published ahead of schedule, here or go back to the start of the series here.

“It’s one small piece of man… one giant leap for mankind,” headlined the Mirror newspaper on 27 June 2000. “Joy as scientists crack DNA code of life!”

The announcement of the completed first draft of the human genome on 26 June 2000 was big news, with a packed press conference at the Wellcome Trust and a video link-up between UK Prime Minister Tony Blair and US President Bill Clinton. A stunning acceleration in sequence production by the main centres in the Human Genome Project saw them go from having 6% in 1998, to 90% of the human genome sequenced less than two years later.

A year later, the Human Genome Project and Celera Genomics – a private company competing to be the first to sequence the human genome – both published their draft sequence. The article by Celera Genomics showed that the draft sequences from the two companies were comparable, containing similar gaps and ambiguities in the sequence.

What did the draft sequence of the human genome reveal?

The draft sequences revealed a far lower number of genes in the human genome than was expected.

In fact, scientists working in the field and in the project took bets on how many genes would be in the human genome. Known as ‘GeneSweep’, the organiser Ewan Birney took over 400 bets, with the average gene number of the bets sitting at around 60,000 genes and up to 150,000.

In contrast, the draft sequence suggested that there were 30,000-40,000 human genes at most.

More recent analysis suggests that the human genome contains approximately 20,600 protein-coding genes.