Completing the human genome sequence
Why was it so difficult to fully complete the human genome sequence?
The Human Genome Project ended in 2003, but genomic researchers had not yet determined every last base (or letter) of the human genome sequence. Instead, they had only completed about 92% of the sequence at that time. Why did they stop there?

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Woman looking at an incomplete human genome sequence, with A, C, T and Gs, but missing some.
She has doubts and says "Hmm, this doesn't look complete to me."
Last updated: August 10, 2021