First complete human genome sequence (T2T-CHM13)

Since its first release in 2000, the human reference genome had covered only the euchromatic part of the genome and had left important heterochromatic regions unfinished. By the National Human Genome Research Institute's account, the Human Genome Project had mapped about 92 percent of the genome. The missing 8 percent contained numerous genes and much repetitive DNA, and it was comparable in size to an entire chromosome.

The Telomere-to-Telomere (T2T) Consortium set out to sequence the rest, working from a human cell line that carries only one copy of each chromosome, unlike most human cells, which carry two. On 31 March 2022 the consortium published six papers in Science. The main paper, whose joint first authors were Sergey Nurk, Sergey Koren, Arang Rhie and Mikko Rautiainen and whose author list ended with Karen Miga and Adam Phillippy, presented T2T-CHM13. It was a complete sequence of 3.055 billion base pairs, with gapless assemblies of every chromosome except Y, and it corrected errors in the earlier references.

The new sequence added nearly 200 million base pairs containing 1,956 gene predictions, 99 of them predicted to code for proteins. The completed regions included all of the centromeric satellite arrays, recent segmental duplications and the short arms of all five acrocentric chromosomes. The authors wrote that the work made these complex regions available for studies of genetic variation and function.

According to NHGRI, the consortium also found more than 2 million additional variants in the human genome and produced more accurate information about variants in 622 medically relevant genes.