Humans Decoded

Context: 

Scientists have completed the first full and seamless catalog of genetic instructions of humans. It’s expected that research will help to explain how every cell in a human body is created. It will help develop highly effective diagnostic tools and treatments for diseases. 

What is the background?

Nobel Prize-winning Italian-American virologist Renato Dulbecco first pitched the idea to determine the DNA sequence of the entire human genome, way back in 1984.

An international research effort continued under the Human Genome Project.

Thirty-eight years and billions of dollars later, scientists completed the first full and seamless catalog of genetic instructions of humans. According to the Telomere-to-Telomere (T2T) consortium’s collection of papers (recently published in Science), the sequence — comprising more than three billion base pairs across 23 chromosomes — is gapless.

What is DNA sequencing?

Sequencing simply means determining the order of the base pairs in a segment of DNA. Human chromosomes range in size from about 50,000,000 to 300,000,000 base pairs (National Human Genome Research Institute, or NHGRI).

What led to the recent breakthrough?

Over the past decade, two new DNA sequencing technologies emerged that can read longer sequences without compromising accuracy. 

1.) The PacBio HiFi DNA sequencing method can read about 20,000 letters with nearly perfect accuracy. 

2.) The Oxford Nanopore DNA sequencing method can read even more — up to 1 million DNA letters at a time — with modest accuracy. Both were used to generate the complete human genome sequence.

What is the significance of complete genomic sequencing?

It shall help explain how every cell in a human body is created, which may shed light on the treatment, prevention, and cure required for a disease. For instance, The Cancer Genome Atlas (TCGA), a cancer genomics program in the US, has already mapped genomic changes in 33 cancer types in order to improve cancer treatment.

It shall open the door for relatively effective personalized or precision medicine and genome editing in the future.

It should lead to powerful preventive medication and allow us to learn about risks of future illness, besides helping better plan dietary and lifestyle changes.

As DNA sequencing becomes the norm, it’s likely that medical prescriptions will be based on our genes — minimizing side effects and making treatments relatively effective. Currently, there are already over 250 US FDA-approved drugs labeled with pharmacogenomic information that can be prescribed based on a patient’s genetics. 

What is the way forward?

The sequencing is done, but the work is far from over. Researchers now want to decode full sets of DNA from a larger pool of individuals to capture all the variations that exist in human DNA. Already researchers, in a separate project, are building a “human pangenome” representing all the human genetic variations.

A strong set of ethical guidelines encompassing genetic research and editing needs to be formulated. As gapless, human genome sequencing will enable society to select specific embryos to avoid health problems and may lead to the rise of “superhumans”.

Source: This post is created based on the article “Humans Decoded” published in Business Standard on 16th April 2022.