Mapping out the billions of building blocks that make up our genetic code is no small feat. When the Human Genome Project first embarked on this project, technological limitations left researchers with large gaps in the final genetic sequence. By the end of the project in 2003, only 92% of the genome was actually complete – excluding stretches of repetitive DNA segments of unclear function.

Scientists published that remaining 8% yesterday. And now, they can put that genetic “dark matter” under the microscope.

Gabrielle Hartley of the University of Connecticut was part of the team of scientists that helped uncover these repetitive sequences. She explains how these missing pieces fit into the genomic puzzle of the human body, and how the repetitive regions that make up so much of our genetic code shape health, evolution and which genes are turned on or off. The work, she writes, could yield not only a better understanding of the fundamentals of biology but also insights into genetic diseases.

Also today:

Vivian Lam

Assistant Health and Biomedicine Editor

Over half of the human genome contains repetitive DNA sequences whose functions are still not fully understood. Malte Mueller/fStop via Getty Images

The Human Genome Project pieced together only 92% of the DNA – now scientists have finally filled in the remaining 8%

Gabrielle Hartley, University of Connecticut

Advances in technology have enabled researchers to sequence the large regions of repetitive DNA that eluded the Human Genome Project.

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