By Tova Grama
The human genome project, or the complete sequencing of the human genome, was officially completed in 2003. However the Y chromosome hadn’t been included in this incredible feat. Now, 20 years later, the Y chromosome has finally been sequenced.The reason it took longer to sequence the Y chromosome is because it has large amounts of palindromes, or repetitive DNA with more than a million base pairs. This posed significant challenges in completing its sequencing. The primary reason as to why there are large amounts of palindromes is due to the absence of a paired chromosome to swap genetic material prematurely to sexual reproduction.
The primary difficulty of sequencing the Y chromosome was introducing a sequencing technique, cutting up DNA into smaller parts, reading its code, then reassembling to find overlaps. The Y chromosome was made of many repetitive sequences. Still, they accomplished the sequencing by using long-read sequencing technology and new computational assembly methods that are capable of handling repetitive segments. The computational assembly methods transform the information into a usable resource and pinpointed any inversions in the sequence which then allowed for further identification of inversions. This revolutionary project led to further research and provided a reference for other studies in reproduction, population change, and evolution.
Candanosa (2023) a science staff writer at John Hopkins University explains why the sequencing of the Y chromosome became an astounding achievement. The sequencing revealed an additional 41 genes on the chromosome. Additionally, the discovery of the genes’ structures play an important role in the male reproductive system and growth. Also, having the Y chromosome completely mapped out, it can motivate others to further study mutations and their connection to genetic diseases and cancer. Furthermore, high quality genome assemblies and even personalized genomes are now feasible. An additional and unexpected discovery that had been unveiled during this project was that Y chromosomal DNA was mistaken for bacterial DNA in previous studies. This was due to human contamination in the bacterial DNA where human DNA was thought to be a part of the bacterial DNA. Since the Y chromosome had not been sequenced, many papers were published with mistaken information. Since the Y chromosome became sequenced, previous studies on bacterial species genomes have been greatly improved by fixing and updating errors in the research projects.
In conclusion, the sequencing of the Y chromosome is a considerable medical achievement. It not only broadens current scientific knowledge, but also leads others to research more about unknown genetic deformities. This accomplishment does not either signify the end to this research topic but opens the door to a vast plethora of new discoveries, including research on the human pangenome. The pangenome is a new version of genomic advancements as it combines genomic information from individuals of many ancestral backgrounds. Learning more about the pangenome can lead to the discovery of treatments for disorders, and further illustrates why the sequencing of the Y chromosome was an undeniable success.
References
https://hub.jhu.edu/2023/08/23/y-chromosome-sequenced-human-genome/