Karen Miga Fills In the Missing Pieces of Our Genome – Quanta Magazine

In 1990, an international team of scientists began an ambitious attempt to sequence the human genome. By 2001 the Human Genome Project (HGP) had prepared a rough draft, and in April 2003, the draft sequence was declared finished. But Karen Miga, a geneticist now at the University of California, Santa Cruz and the associate director of the UCSC Genomics Institute, knew that while the work might have wrapped up, the sequencing was far from complete.

The HGP was able to sequence the 90% of human DNA that geneticists call euchromatin, which is loosely folded and contains nearly all of the genes that are actively making proteins. But Miga specialized in heterochromatin, the tightly packed sections of DNA with highly repetitive sequences near the ends (telomeres) and centers (centromeres) of chromosomes. At the time, scientists couldnt sequence heterochromatin, so despite the celebratory hubbub and champagne toasts, almost 10% of the genome went unsequenced.

It stayed that way for almost 20 years. The problem nagged at Miga, in part because she didnt believe that the regions were as unimportant as some geneticists thought. (Without a sequence, how could you tell?) Over the years, Miga continued to push the genomics field to complete the project they had started so many years before. As DNA sequencing technologies enabled researchers to read longer and longer stretches of the genome in one go, Miga could see that scientists were inching closer to the possibility of cracking the problem open.

Together with Adam Phillippy, a computational biologist at the National Human Genome Research Institute, Miga launched the Telomere-to-Telomere (T2T) consortium in 2018 to finally sequence every last nucleotide of human DNA. Then, just as the team was finding its footing, the pandemic struck.

But COVID-19 didnt stop their progress. In June, Miga, Phillippy and their colleagues published the first complete genome sequence on the preprint server biorxiv.org. Three decades after it began, the human genome was finally complete.

Quanta sat down with Miga in a video chat to discuss her years of work and what the consortiums accomplishment might mean for science. The interview has been condensed and edited for clarity.

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Karen Miga Fills In the Missing Pieces of Our Genome - Quanta Magazine