Scientists Solve Sex-Related Y-Chromosome Genetic Conundrum

WASHINGTON, Aug 23 (Reuters) – Scientists have taken a major step forward in understanding the Human genome -our genetic model- by completely deciphering the enigmatic Y chromosome present in men, an achievement that could help guide research on infertility in men.

Researchers on Wednesday revealed the first complete sequence of the human Y chromosome, which is one of the two sex chromosomes (the X chromosome is the other) and is normally passed from father to son. It is the last of the 24 chromosomes (threadlike structures that carry genetic information from one cell to another) in the human genome to be sequenced.

People have one pair of sex chromosomes in each cell. Males have one Y chromosome and one X chromosome, while females have two X chromosomes, with a few exceptions.

Genes on the Y chromosome help regulate crucial reproductive functions, including sperm production, formally called spermatogenesis, and are even involved in cancer risk and severity. But this chromosome proved difficult to decipher due to its exceptionally complex structure.

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

“It finally provides the first complete view of the code of a Y chromosome, revealing more than 50% of the chromosome length that was previously missing from our genomic maps,” said the University of California Santa Cruz (UCSC) professor of biomolecular engineering. and co-author of the study. Author Karen Miga, co-director of the Telomere-to-Telomere consortium behind the research.

The complete sequence of the X chromosome was published in 2020. But until now, the Y chromosome part of the human genome contained large gaps.

“This is especially important because the Y chromosome has traditionally been excluded from many studies of human disease,” said Monika Cechova, a UCSC genomics and study co-author.

“The Y chromosome is the smallest and fastest evolving chromosome in the human genome, and also the most repetitive, which means that its DNA contains stretches of DNA that are repeated many times,” Cechova added.

The work revealed features of medically relevant regions of the Y chromosome, including a stretch of DNA (the molecule that carries genetic information for the development and function of an organism) that contains several genes involved in sperm production. According to the researchers, the new, more comprehensive understanding of Y-chromosome genes holds promise for practical applications, including fertility-related research.

“Many of these genes are important for fertility and reproduction, and especially for spermatogenesis, so being able to catalog the normal variation, as well as the situations in which, for example, azoospermia occurs (absence of sperm in the semen), could be useful for IVF (in vitro fertilization clinics), as well as further research on the activity of these genes,” Cechova said.

In addition to identifying some additional genes on the Y chromosome, the researchers found that previous studies had mistaken some of the chromosome’s DNA for bacterial nature.

Scientists continue to expand our understanding of human genetics. In 2003, a first description of the human genome was released. complete human genome -albeit with a partial Y chromosome- was published last year. In May, the researchers published a new version of the genome which improved on its predecessor by including a rich diversity of people to better reflect the world’s population of 8 billion.

To this is added the complete sequencing of the Y chromosome.

“We now have a recipe for how to fully assemble the Y chromosome, which, while expensive at the moment, may translate into personalized genomics in the future,” Cechova said.

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