(CTN NEWS) – Nevertheless, more than half of the sequences housed within the Y chromosome, which is not only the tiniest but also the most intricate among the 46 human chromosomes, remained shrouded in mystery.
Nonetheless, the same team of researchers has now demystified this enigma by revealing a comprehensive sequence of the Y chromosome. Their findings were published on Wednesday in the journal Nature.
“Only a few years ago, the reference lacked over fifty percent of the human Y chromosome,” stated Monika Cechova, one of the co-lead authors of the study and a postdoctoral scholar specializing in biomolecular engineering at the University of California, Santa Cruz.
She further remarked, “At that time, we weren’t even certain if it was feasible to sequence it due to its perplexing nature. This truly marks a monumental shift in our possibilities.”
The Significance of the Y Chromosome: Exploring Genetics and Health
Typically, individuals possess a pair of sex chromosomes within each cell. Those identified as male at birth carry an X and a Y chromosome, while individuals designated as female at birth possess two X chromosomes.
The enhanced and intricate details furnished by the novel Y reference sequence will facilitate the investigation of conditions and disorders associated with this chromosome. These include instances such as the absence of sperm production leading to infertility.
Recent studies propose that the Y-chromosome also plays a significant role in maintaining health and extending lifespan.
Kenneth Walsh, a professor specializing in biochemistry and molecular genetics at the University of Virginia School of Medicine, and not connected with the recent research, pointed out that
“Genes located on the Y-chromosome have been pinpointed as crucial for safeguarding against cancer and cardiovascular ailments,” as conveyed through email.
“It’s been like unraveling the ‘dark matter’ of the genome,” he remarked. “This fresh analysis will grant us a clearer comprehension of the segments within the Y chromosome that possess regulatory roles and the potential to encode mRNA and proteins.”
As individuals age, particularly in cells that undergo rapid turnover like blood cells, many begin to experience Y chromosome loss in certain cells.
Y Chromosome’s Impact on Health: Unveiling the Enigma
The reasons behind this occurrence and its implications for an individual’s health have never been fully grasped. Nevertheless, recent scientific studies have associated this phenomenon with heightened severity of bladder cancer and an increased risk of heart disease.
Possessing a comprehensive genetic reference of the Y chromosome might empower scientists and medical professionals to delve deeper into this possible correlation.
“Considering the link between the Y chromosome and age-related illnesses, these studies likely scratch the surface,”
Walsh explained. He added that the decline of the Y chromosome might partially elucidate the shorter lifespan observed in men compared to women in Western industrialized nations (men generally live about six years less than women).
“Yet, there has been speculation whether Y chromosome loss signifies a biomarker of biological aging or whether it directly impacts men’s health,” he stated. “Recent research furnishes compelling evidence to support a direct effect.”
Cracking the Y chromosome posed an especially challenging task due to its remarkable level of repetition.
DNA’s composition relies on four fundamental letters or building blocks — adenine (A), cytosine (C), guanine (G), and thymine (T) — which form distinct pairs, binding together in the iconic double helix configuration. Chromosomes, threadlike formations, are comprised of DNA.
While repeats exist in all human chromosomes, the Y chromosome stands out with over 30 million letters out of its total 62.5 million being composed of repetitive sequences, often referred to as satellite DNA or junk DNA.
Additionally, the Y chromosome hosts palindromes — strings of letters that read the same forwards and backwards, akin to the term “radar.”
“The Y chromosome is not only the smallest, but it also boasts the highest complexity, featuring an extensive amount of repetitive DNA.
These are like segments of DNA that are reiterated numerous times, sometimes in a sequential manner and occasionally interwoven with distinct sequences,” explained Cechova.
The intricacy of repetitive DNA introduces complexities due to the analogy that assembling genetic sequencing data is akin to deciphering a lengthy book divided into strips, as described by the National Human Genome Research Institute.
“If each line in the book is unique, establishing the correct order is relatively straightforward.
However, when the same sentence repeats thousands or millions of times, the original strip arrangement becomes significantly less evident,” highlighted the institute, which funds the T2T Consortium, in a press release.
In the instance of the Y chromosome, it’s comparable to having the same few sentences reiterated for half the extent of the book.
Revolutionizing Genetic Exploration: Decoding the Y Chromosome
Through the utilization of innovative “long-read” sequencing technology and advanced computational techniques capable of managing repetitive sequences and translating raw data into a practical resource, the researchers triumphantly accomplished a comprehensive examination of the Y chromosome.
The fully deciphered Y chromosome introduces over 30 million base pairs, primarily consisting of repetitive sequences, into the human reference genome.
Earlier this year, scientists curated a “pangenome” by amalgamating the DNA of numerous individuals hailing from nearly every corner of the globe. This effectively modernized the human genome, fostering a more just and inclusive representation.
In a concurrent study published in the same journal on the same day, a collaborative group of researchers amassed Y chromosomes from 43 male subjects across 21 global populations, capturing the genetic diversity within the Y chromosome.
“Mounting evidence suggests that optimal gene function within the Y chromosome holds profound significance for men’s overall well-being,” remarked Charles Lee, a senior author of the companion research paper and a professor as well as the research director at the Jackson Laboratory for Genomic Medicine.
He further stated, “Our investigation permits the integration of the complete Y chromosome into all forthcoming studies involving the sequencing of male genomes, facilitating the comprehension of health and disease.”
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