The release of the draft human genome sequence in 2001 was a seismic moment in our understanding of the human genome
Jun 10, 2021
11:10 AM (IST)
The release of the draft human genome sequence in 2001 was a seismic moment in our understanding of the human genome and paved the way for advances in our understanding of the genomic basis of human biology and disease.
But sections were left unsequenced, and some sequence information was incorrect. Now, two decades later, we have a much more complete version, published as a preprint (which is yet to undergo peer review) by an international consortium of researchers.
Technological limitations meant the original draft human genome sequence covered just the “euchromatic” portion of the genome — the 92% of our genome where most genes are found, and which is most active in making gene products such as RNA and proteins.
The newly updated sequence fills in most of the remaining gaps, providing the full 3.055 billion base pairs (“letters”) of our DNA code in its entirety. This data has been made publicly available, in the hope, other researchers will use it to further their research.
Much of the newly sequenced material is the “heterochromatic” part of the genome, which is more “tightly packed” than the euchromatic genome and contains many highly repetitive sequences that are very challenging to read accurately.
These regions were once thought not to contain any important genetic information but they are now known to contain genes that are involved in fundamentally important processes such as the formation of organs during embryonic development. Among the 200 million newly sequenced base pairs are an estimated 115 genes predicted to be involved in producing proteins.
The newly published genome sequence was created using human cells derived from a very rare type of tissue called a complete hydatidiform mole, which occurs when a fertilised egg loses all the genetic material contributed to it by the mother.
Most cells contain two copies of each chromosome, one from each parent and each parent’s chromosome contributing a different DNA sequence. A cell from a complete hydatidiform mole has two copies of the father’s chromosomes only, and the genetic sequence of each pair of chromosomes is identical. This makes the full genome sequence much easier to piece together.
After decades of glacial progress, the Human Genome Project achieved its 2001 breakthrough by pioneering a method called “shotgun sequencing”, which involved breaking the genome into very small fragments of about 200 base pairs, cloning them inside bacteria, deciphering their sequences, and then piecing them back together like a giant jigsaw.
This was the main reason the original draft covered only the euchromatic regions of the genome — only these regions could be reliably sequenced using this method.
The latest sequence was deduced using two complementary new DNA-sequencing technologies. One was developed by PacBio, and allows longer DNA fragments to be sequenced with very high accuracy. The second, developed by Oxford Nanopore, produces ultra-long stretches of continuous DNA sequence. These new technologies allows the jigsaw pieces to be thousands or even millions of base pairs long, making them easier to assemble.
The new information has the potential to advance our understanding of human biology including how chromosomes function and maintain their structure. It is also going to improve our understanding of genetic conditions such as Down syndrome that have an underlying chromosomal abnormality.
Well, no. An obvious omission is the Y chromosome because the complete hydatidiform mole cells used to compile this sequence contained two identical copies of the X chromosome. However, this work is underway and the researchers anticipate their method can also accurately sequence the Y chromosome, despite it having highly repetitive sequences.
Even though sequencing the (almost) complete genome of a human cell is an extremely impressive landmark, it is just one of several crucial steps towards fully understanding humans’ genetic diversity.
The next job will be to study the genomes of diverse populations (the complete hydatidiform mole cells were European). Once the new technology has matured sufficiently to be used routinely to sequence many different human genomes, from different populations, it will be better positioned to make a more significant impact on our understanding of human history, biology and health.
Both care and technological development are needed to ensure this research is conducted with a full understanding of the diversity of the human genome to prevent exacerbation of health disparities by limiting discoveries to specific populations. (The Conversation)
What do you think? (Share your feedback)
‘Course-correct’, AICC panel to Punjab CM; wants Navjot Sidhu ‘suitably accommodated’
Unplanned vaccination can promote mutant Covid strains: Health experts in report to PM
US to accept student visa applications from June 14
8 children among 11 die in Malwani building collapse in Mumbai
Did Nusrat Jahan â????lieâ???? in Parliament, BJPâ????s Amit Malviya gives new twist to TMC MPâ????s marital status row
SUBSCRIBE TO OUR NEWSLETTER
9 succumb to virus, 104 test positive in Amritsar
Open malls, eateries on lines of Chandigarh, say Amritsar traders
Amritsar libraries preserving a treasure trove of books
When two Punjabs met
Unable to satiate your taste buds? First, check the oil your pakoras are fried in
MSP hike not enough, say farmers
International-level karate player working as labourer in paddy fields in Punjab’s Mansa
Bathinda teachers protest transfer delay
Chandigarh records 66 new cases, 6 deaths
Rain brings relief from hot weather for tricity residents
Life goes on for them, â????blissfullyâ???? untouched by Covid
Life limps back to normalcy in Chandigarh
Chandigarh Administration steps in, now no more fleecing by private hospitals
Delhiâ????s first smog tower will be ready by August 15: Environment Minister Gopal Rai
Sweltering in Delhi as mercury remains above 40
Group of students broke into central library, clashed with staff; FIR registered: JNU
Oxygen storage capacity ramped up in Delhi
Tap resources to raise funds for rural sanitation: Govt to states
Covaxin trouble for foreign-bound students?
6 deaths, 142 test ve in Jalandhar district
Turncoats change political equation in Doaba
Hoshiarpur DC in driverâ????s seat to promote direct sowing of paddy
Punjabi singer Imran Khan arrested by Kapurthala police for hosting birthday party
Covid -19: Virus claims 8 lives in Ludhiana
1,310 auxiliary polling stations to be set up in Ludhiana district for Assembly polls
e-auction of plots at upcoming hi-tech cycle valley soon in Ludhiana
Ludhiana Municipal Corporation forms five rescue teams for monsoon
Illegal hoardings cover direction signboards, commuters suffer in Ludhiana
Playing safe, Patiala admn sets up task forces to tackle â????3rd Covid waveâ????
3 of gang arrested on charge of car thefts
Spend money on healthcare, not installation of statues, say Patiala residents
Dharamshala work begins
The Tribune, now published from Chandigarh, started publication on February 2, 1881, in Lahore (now in Pakistan). It was started by Sardar Dyal Singh Majithia, a public-spirited philanthropist, and is run by a trust comprising five eminent persons as trustees.
The Tribune, the largest selling English daily in North India, publishes news and views without any bias or prejudice of any kind. Restraint and moderation, rather than agitational language and partisanship, are the hallmarks of the paper. It is an independent newspaper in the real sense of the term.
Designed and Developed by: Grazitti Interactive
– Why it took 20 years to 'finish' the human genome — and why there's still more to do
– World News | Why It Took 20 Years to 'finish' the Human Genome — and Why There's Still More to Do
Genome,Human Genome Project,Genome, Human Genome Project,,