Scientists finally complete genome sequencing of Y chromosome

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Scientists finally complete genome sequencing of Y chromosome

In a first, scientists have completed the long-anticipated genome sequencing of male Y chromosomes, finally mapping the set of end-to-end human chromosomes.

The human Y chromosome — one of the two human sex chromosomes — has been notoriously difficult to sequence and assemble because of its complex repeat structure that includes long palindromes, tandem repeats and segmental duplication, said researchers from the the Telomere-to-Telomere (T2T) consortium, in the paper published in the journal Nature.

The T2T consortium, part of the Human Genome project, sequenced the entire human genome from a cell with XX chromosomes last year.

“Just a few years ago, half of the human Y chromosome was missing [from the reference] — the challenging, complex satellite areas,” said Monika Cechova, co-lead author on the paper and postdoctoral scholar in biomolecular engineering at University of California, Santa Cruz.

Scientists finally complete genome sequencing of Y chromosome

Scientists finally complete genome sequencing of Y chromosomeIANS

“Back then we didn’t even know if it could be sequenced, it was so puzzling. This is really a huge shift in what’s possible.”

The Y chromosome is most commonly associated with individuals assigned male at birth, but may be found in others, such as intersex people.

The sex characteristics regulated by DNA on the Y chromosome are also not equivalent to an individual’s gender identity.

Until now, the Y chromosome portion of the human genome has contained large gaps which made it difficult to understand variation and associated disease.

The researchers were able to achieve a gapless read of the Y chromosome due to advances in long-read sequencing technology and new, innovative computational assembly methods that could deal with the repetitive sequences and transform the raw data from sequencing into a usable resource.

DNA double helix

A DNA double helix is seen in an undated artist’s illustration released by the National Human Genome Research InstituteREUTERS/National Human Genome Research Institute/Handout

While there are relatively few genes on the Y chromosome, the ones that are present are complex and dynamic, and code for important functions such as spermatogenesis, the production of sperm.

The end-to-end Y chromosome sequence is a hugely important resource for those studying human population evolution and drift.

This is because the Y chromosome is inherited from generation to generation in one group of genetic material, with very little recombination outside of that group, unlike the autosomes and genes on the human X chromosome which often recombine and share genetic material with each other.

Even within the Y chromosome, the genes are split into several regions, which are very different from each other in terms of content, structure, and evolutionary history.

Understanding rates of change on the Y chromosome and how to interpret this change are intriguing questions that will now be possible to study using the techniques developed in this paper to completely sequence human Y chromosomes.

It’s been shown that people with Y chromosomes can lose some or all of that genetic material as they age, but scientists have never fully understood why this happens and the effects it may have.

The complete Y chromosome reference may help to illuminate this mystery.

(With inputs from IANS)

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