Visiškai žmogaus genomas sequence of the two X chromosomes and autosomes from the female tissue derived cell line has been completed. This includes the 8% of the genomas sequence that was missing in the original draft that was released in 2001.
Visiškai žmogaus genomas sequence of the entire 3.055 billion base pairs has been revealed by the Telomere-to-Telomere (T2T) Consortium. This represents the largest improvement to the žmogaus nuoroda genomas released in 2001 by Celera Genomics and the International Žmonių Genomas Sequencing Consortium. That genomas sequence covered most of the euchromatic regions while either leaving out the heterochromatin regions or erroneous representation. These regions comprise 8% of the žmogaus genomas that has finally been revealed. The new T2T-CHM13 reference1 apima visą seką visoms 22 autosomoms ir X chromosomą. Ši nauja etaloninė seka taip pat ištaisė daugybę klaidų ir pridėjo maždaug 200 milijonų bp naujų sekų, turinčių 2,226 genų kopijas, iš kurių 115, kaip manoma, koduoja baltymus.
The current GRCh38.p13 reference genome has been as a result of two major updates, one in 2013 and the other one on 2019 on the 2001 Celera genome sequence. However, it still had 151 million base pairs of unknown sequence distributed throughout the genomas, including pericentromeric and sub telomeric regions, duplications, gene and ribosomal DNA (rDNA) arrays, all of which are necessary for fundamental cellular processes. The new reference has been named as T2T-CHM13 as it comes from sequencing the DNA from CHM13 (Complete Hydatiform Mole) cell line and is performed by T2T consortium. The cell line is derived from abnormal fertilized egg or an overgrowth of tissue from the placenta in which women appears to be pregnant (false pregnancy), hence the sequence represents only of the two X chromosomes and autosomes of the female. Multiple sequence technologies have been put to use such as PacBio, Oxford Nanopore, 100X and 70X Illumina sequencers to name a few. The technological advances in sequencing have led to the sequencing of the remaining 8% as mentioned above.
Vienintelis T2T-CHM13 sekos apribojimas yra Y chromosomos nebuvimas. Šiuo metu vyksta seka, naudojant DNR iš HG002 ląstelių linijos, kuri turi 46 (23 poras) su XY kariotipu. Tada seka bus surinkta naudojant tuos pačius metodus, sukurtus homozigotiniam CHM13 genomui.
T2T-CHM13 prieinamumas kaip nauja nuoroda genomas yra didelis laimėjimas, kuris padės suprasti heterochromatino regionų vaidmenį ir padės suprasti jo poveikį ląstelių procesams. Kol bus baigtas Y chromosomos sekos nustatymas, tai bus etaloninis genomas būsimiems tyrimams, siekiant suprasti ląstelių procesus ir funkcijas.
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Nuorodos
- Nurk S, Koren S, Rhie A, Rautiainen M, Bzikadze A V, Mikheenko A et al. The complete sequence of a žmogaus genome bioRxiv 2021.05.26.445798; DOI: https://doi.org/10.1101/2021.05.26.445798
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