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

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

The announcement of the completion of the 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. After 1998, a stunning acceleration in sequence production by the main centres in the Human Genome Project saw them go from having six per cent of the human genome sequenced to 90 per cent sequenced in under two years.

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

A year later, the Human Genome Project and Celera Genomics, (a private company competing with the Human Genome Project to be the first to sequence the human genome), both published their findings, in Nature and Science magazine, respectively. The article by Celera Genomics in Science included a report on the assembly of their ‘draft’ human genome and a comparison between the Human Genome Project and Celera Genomics sequences. It showed that the draft sequences from the two companies were comparable, containing similar gaps and ambiguities in the sequence.

However, the draft sequences also revealed a far lower number of genes in the human genome than was expected. Previously, numbers up to and beyond 150,000 genes had been forecast but to the surprise of many, 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 21,000 protein-coding genes.

Dr. Ewan Birney, Joint Associate Director and Senior Scientist at the European Bioinformatics Institute (EBI).

Critics argued that Celera Genomics’ assembly would have been impossible without the Human Genome Project’s data.

Despite the Human Genome Project and Celera Genomics finishing their drafts around the same time. Celera Genomics were criticised for the methods they used. It was suggested that they had generated their sequence using Fred Sanger’s shotgun sequencing method, skipping the mapping phase of the process and using the map created by the public effort instead. This is what allowed them to finish the sequencing process in just three years. Critics argued that such an assembly would be impossible at the time without the Human Genome Project’s data.

Having said this, the announcement of the first draft marked the finishing line of the ‘race’ between the public and private initiatives.