For the first time, scientists have fully sequenced the Y chromosome, twenty years after the completion of the Human Genome Project. The Y chromosome is one of the smallest chromosomes and has the fewest genes coding for proteins. It is also known for accumulating bits of repetitive DNA. Previous methods of DNA sequencing were unable to accurately sequence repetitive DNA.
In 2021, a team of researchers finally filled in the gaps and completed the Y chromosome sequence using a technique developed by Oxford Nanopore. This technique allows for the sequencing of a single DNA molecule as it passes through a tiny hole, producing longer DNA sequences. The completed genome sequenced by the researchers was from a person of European descent.
The complete Y chromosome sequence contains 106 protein-coding genes, which is 41 more than the reference genome. However, most of these extra genes are copies of the same gene called TSPY. Another team, led by Charles Lee, sequenced the Y chromosomes of 43 diverse men, including individuals of African descent. However, most of their sequences still have gaps.
The Y chromosome sequences show considerable diversity among individuals, with variations in the number of copies of the TSPY gene. The researchers believe there is still much to learn about repetitive DNA and its importance, as it is often dismissed as “junk” DNA. However, the sequencing of the Y chromosome has not revealed much new information about the parts of the chromosome that include genes.
This achievement represents an incremental advance in our understanding of the Y chromosome’s genetics, particularly the euchromatic portions that contain genes. Further research is needed to unravel the significance of repetitive DNA and its functions.
