This was reported according to New Scientist’s Ukrinform report.

It is stated that most people have 22 pairs of chromosomes and two sex chromosomes (one pair of X chromosomes or one X and one Y chromosome). The presence of the Y chromosome often (but not always) leads to the development of male characteristics in the embryo.

Y is one of the smallest chromosomes and has the fewest number of protein-coding genes. It is particularly likely to accumulate repetitive DNA regions, as it does not normally have a paired chromosome that can switch regions prior to sexual reproduction.

All of the early methods of sequencing DNA involved breaking it up into small pieces, reading their genetic code, and then putting the pieces together by looking for matches. This method does not work with repetitive DNA where many parts are the same.

The Y chromosome was partially sequenced in 2003, but only 50% of the code was identified at that time.

But in 2021, a group of experts, including Karen Miga of the University of California, filled almost all the gaps and declared the human genome “complete” again. This is made possible by technology developed by Oxford Nanopore that reads the sequence of a single DNA molecule as it passes through a small hole, resulting in fragments of millions of DNA letters instead of a few hundred.

But the “complete” genome sequenced by Miga and colleagues was female, consisting of 22 normal chromosomes and one X chromosome. Miga’s colleagues have only now completed sequencing of the Y chromosome from a person of European descent.

“The Y chromosome is full of complex structures and contains huge areas where the same code blocks are repeated over and over with minor changes, making it extremely difficult to put together. The ability to sequence DNA fragments of any length was absolutely essential for this project.” – says Serhii Nurk, who worked on the project.

As noted, the entire Y chromosome contains 106 protein-coding genes; this is 41 more genes than in the “reference” genome. But almost all of the extra genes are copies of a single gene called TSPY.

Meanwhile, Charles Lee’s group at the Jackson Genomic Medicine Laboratory sequenced the Y chromosomes of 43 different men, including 21 African men. But he said that only three Y-sequences obtained by his team found no gaps. Others have one to five spaces.

According to Lee, the 43 Y chromosomes are quite diverse. For example, the copy number of the TSPY gene ranges from 23 to 39.

As Ukrinform reports, a group of scientists from the Chinese Academy of Sciences has sequenced the genome from late Pleistocene human remains in the southwestern region of the country.

Photograph: BIOPHOTO ASSOCIATES/Science Photo Library