Scientists have taken a major step forward in understanding the human genome – our genetic imprint – by fully deciphering the enigmatic Y chromosome present in men, an achievement that could help research into infertility, Reuters reported on Wednesday. Agerpres.

Researchers on Wednesday revealed the first complete sequence of the human Y chromosome, which is one of two chromosomes responsible for determining sex (the X chromosome being the other) and is usually passed from male parents to same-sex offspring. It is the last of the 24 chromosomes—the threadlike structures that carry genetic information from cell to cell—in the human genome to be sequenced.

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

Genes on the Y chromosome control basic reproductive functions, including the production of sperm – a process called spermatogenesis – and are even implicated in the risk and severity of cancer. However, this chromosome proved difficult to sequence due to its extremely complex structure.

“I would prefer this to new sequencing technologies and computational methods,” said Arang Rhee, a scientist at the US Human Genome Research Institute and lead author of a scientific paper detailing the breakthrough in the journal Nature.

This achievement “finally provides the first complete insight into the Y chromosome code, revealing more than 50% of the length of the chromosome that was previously missing from our genome maps,” said Karen Miga, professor of biomolecular engineering at the University of California, Berkeley, Santa Cruz (UCSC ), co-author of the study. She is one of the researchers leading the Telomere-to-Telomere Consortium behind the study.

The complete sequence of the X chromosome was published in 2020. However, until now, part of the Y-chromosome of the human genome had significant gaps.

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

“The Y-chromosome is the smallest and most rapidly evolving chromosome in the human genome and at the same time the most repetitive, which means that its DNA contains parts of DNA that are repeated many times,” added Chekhova.

The study revealed characteristics of medical regions of the Y chromosome, including a section of DNA — the molecule that carries genetic information for the body’s development and functioning — containing several genes involved in sperm production.

According to scientists, new, deeper information about the genes of the Y-chromosome gives hope for practical application, including in the field of fertility research.

“Many of these genes are important for fertility and reproduction, and especially for spermatogenesis, so being able to catalog normal variations as well as situations in which, for example, azoospermia (absence of sperm, which determines sterility) occurs can be useful for IVF clinics. fertilization), as well as for additional studies of the activity of these genes,” said Chekhova.

In addition to identifying additional genes on the Y chromosome, the researchers discovered that the nature of some DNA components on this chromosome had been mistaken in previous studies as bacterial.

Scientists continue to expand their understanding of human genetics. The first sequencing of the human genome was revealed 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 previous information by including a greater diversity of people to better reflect the global population of 8 billion.

Complete sequencing of the Y chromosome is complementary to this. “We now have a recipe for how the Y-chromosome can be completely assembled, which, although expensive at the moment, could turn into personalized genomics in the future,” said Monika Chekhova.