What is Human Genome Mapping?

On February 12, 2001, the rough draft of the complete sequence of the human genome was unveiled at Washington, DC. The publication was the result of years of work by hundreds of scientists from all over the world who were part of an international research project called the Human Genome Project (HGP).

The HGP gave us the ability to arrive at a master blueprint of the genetic makeup of homo sapiens. It is a great feat in our endeavour to explore human history. The mapping also has tremendous significance in molecular medicine.

While taking a look at the HGP, we will also touch upon the subject of genome and DNA sequencing in this Explainer.

When did the Human Genome Project begin?

The Human Genome Project was started in 1990 and was completed in 2003. It was funded by the U.S. government through the National Institutes of Health (NIH) as well as numerous other groups from around the world. The project was expected to take 15 years and cost $3 billion. But it was completed in 13 years and at a cost less than the estimated budget, due to advancements in research and technology in the subsequent years.

Most of the sequencing was performed in 20 universities and research centres in the United States, the United Kingdom, Japan, France, Germany, Spain and China. James Watson, one of the scientists who discovered the double helix structure of the DNA was appointed to lead the National Human Genome Research Institute, a wing of the NIH.

What is genome?

You must have studied about genes in your biology class. Let’s brush up on the basics before delving into the details of the HGP.

A gene is the basic physical and functional unit of heredity. Genes carry the information that determines your traits features or characteristics – passed on to you from your parents. For instance, if your parents have curly hair, you may inherit this trait from them.

Genes are found on tiny spaghetti-like structures inside your cells called chromosomes and are made up of a chemical compound called the deoxyribonucleic acid (DNA), which contains the genetic instructions for the development and functioning of your cells. A genome of an organism is the organism’s complete set of genetic information.

What is DNA sequencing?

The DNA molecule consists of two strands that wind around each other to form a shape known as a double helix. Each strand is composed of long sequences of the four nucleotide bases, A C, G and T, standing for adenine, thymine, cytosine, and guanine. Within the DNA molecule, A pairs only with T, and C pairs only with G.

DNA sequencing is the process of determining the sequence/ order of nucleotides (As, Ts, Cs, and Gs) in a piece of DNA. Sequencing a short piece of DNA is easy, but sequencing an entire genome remains a complex task. Why wouldn’t it be, given the fact that the human genome contains approximately 3 billion of these base pairs, which reside in the 23 pairs of chromosomes within the nucleus of all our cells?

Whose DNAs were studied for the HGP?

The sequence was derived from the DNA of several volunteers, whose identities were not revealed. According to the National Human Genome Research Institute, candidates were recruited from a diverse population. The volunteers responded to local public advertisements near the laboratories where the DNA “libraries” were prepared. Their blood samples were collected for the study.

What did the first draft find out?

This first draft published on Feb, 2001, had information on the entire human genome’s three billion base pairs. More than 2,800 researchers who took part in the consortium shared authorship. In the words of Francis Collins, then director of the National Human Genome Research Institute, “It’s a shop manual, with an incredibly detailed blueprint for building every human cell. And it’s a transformative textbook of medicine, with insights that will give healthcare providers immense new powers to treat, prevent and cure disease.

The HGP revealed that there are probably about 20,500 human genes, significantly fewer than previous estimates, which ranged from 50.000 genes to as many as 140,000. Researchers also reported that the DNA sequences of any two humans are 99.9% identical.

In 2003, the final report of the complete human genome sequence was published. This sequence of the DNA is stored in databases available to anyone on the Internet – one of the significant aspects of this project.

How can this genetic data help humanity?

Knowledge of genetic data has paved the way for new research and possibilities in diagnosing diseases connected to genes, early detection of certain diseases, and gene therapy. It enables us to identify genetic variants linked to certain diseases. The project raised hope that one day scientists will be able to look at an individual’s DNA and prescribe personalised medicines or even prevent certain diseases. The Human Genome Project also proves to be a valuable new tool for studying human origins and the history of our species’ migration.

 

Picture Credit : Google

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