Scientists have solved the genetic puzzle of the sex-linked Y chromosome – Sce

WASHINGTON, Aug 23 (Reuters) – Scientists have taken a major step forward in understanding the human genome – our genetic blueprint – by fully deciphering the mysterious Y chromosome present in men, an achievement that could help guide research into male infertility.

On Wednesday, researchers unveiled the first complete sequence of the human Y chromosome, which is one of two sex chromosomes — the X chromosome is the other — and is usually passed down from male parents to male offspring. It is the last of the 24 chromosomes – the thread-like structures that carry genetic information from cell to cell – to sequence in the human genome.

Each human cell contains a pair of sex chromosomes. Males have one Y and one X chromosome while females have two X chromosomes, with few exceptions.

Genes on the Y chromosome help manage important reproductive functions, including sperm production, formally called spermatogenesis, and have even been linked to cancer risk and severity. But this chromosome proved difficult to crack due to its exceptionally complex structure.

“I would credit the new sequencing technology and computational methods for this,” said Arang Rai, a staff scientist at the US National Human Genome Research Institute and lead author of a paper detailing the achievement in the journal. the nature.

“This finally provides the first complete view of a Y chromosome’s code, revealing more than 50% of the length of the chromosome that was previously missing from our genome map,” said University of California, Santa Cruz (UCSC) biomolecular engineering professor and study co-author Karen Miga. , co-leader of the Telomere-to-Telomere Consortium behind the research.

The complete X chromosome sequence was released in 2020. But until now, there are large gaps in the Y chromosome segment of the human genome.

“This is particularly important because the Y chromosome has traditionally been excluded from many studies of human disease,” said UCSC genomicist and study co-author Monica Chechoa.

“The Y chromosome is the shortest and fastest growing chromosome in the human genome, and the most repetitive, meaning that its DNA contains stretches of DNA that are repeated many times,” Chechoa added.

The work revealed the properties of medically relevant regions of the Y chromosome, including a stretch of DNA – the molecule that carries genetic information for an organism’s development and function – containing several genes involved in sperm production. According to the researchers, the new comprehensive understanding of genes on the Y chromosome promises practical applications, including reproductive-related research.

“Many of these genes are important for fertility and reproduction, and especially for spermatogenesis, so being able to catalog normal changes as well as situations when, for example, azoospermia (absence of sperm in semen) occurs, could be helpful for IVF (in vitro fertilization) activity of these genes in the clinic. More research about,” says Chechova.

In addition to identifying some additional Y chromosome genes, the researchers found that some DNA from the chromosomes had been mistaken in previous studies as bacterial in nature.

Scientists continue to expand the understanding of human genetics. The first accounting of the human genome was unveiled in 2003. The first complete human genome – albeit with a partial Y chromosome – was published last year. In May, researchers released a new version of the genome that improved on its predecessor by incorporating the rich diversity of humans to better reflect a global population of 8 billion.

Sequencing the Y chromosome in its entirety adds to this.

“We now have a recipe for fully assembling the Y chromosome, which, while expensive at the moment, could translate into personalized genomics in the future,” Chechoa said.

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