The Human Genome Project:
Was it really completed over a decade ago?
As members of humanity, we are entitled to 23 pair of chromosomes. All of our 30,000 genes reside on these chromosomes. The Human Genome Project (HGP) was a collaboration between scientists and the US Department of Energy, and a private company, Celera Genetics. Its task was to map all human genes, to know their location and their genetic code. Each gene is composed of DNA which in turn is composed over only 4 chemicals called nucleotides…adenine, thymine, guanine, cytosine. It is the order of these 4 nucleotides that determine all human function and features. To understand the magnitude of the HGP, you should know that there are approximately 30 billion nucleotides to decode.
Ten years later, in the year 2000, with great fanfare and pomp, it was announced that we have decoded or sequenced the complete human genome. There was only one problem, the entire genome had not been decoded. What was completed can best be considered a rough draft. Then again, in 2003 the HGP was again declared complete. Even this new version was missing 8% of the genome. https://www.genome.gov/human-genome-project The technology in 2003 was simply incapable of reading the DNA genetic code from the most difficult areas of the chromosomes.
A careful look at human chromosomes will alert you to the fact that not only do chromosomes come in pairs but are joined by a structure called the centromere. Most centromeres are near the center, but in 5 of our 23 chromosomes they reside at or near the end (see images)
The centromere, and the short arms of the chromosomes are particularly rich in DNA. In 2003, the DNA code was very difficult to read. Many of these segments do not contain genes but contain DNA thought to be important in regulating cell division. When a cell divides, the DNA, and chromosomes double so that each cell can receive 23 chromosomes. The DNA at the centromere assures that each cell during division, gets an equal share of chromosomes. Examples of defective proper chromosome separation include Down, Turner, and Klinefelter syndromes. Scrutinizing the DNA gene code may yield clues to other chromosomal abnormalities. Now 2 companies (PacBio Hi Fi and Oxford Nanopore) have developed new technology slowing scientists to read the genetic code at the centromere and of the short arm of the chromosomes.
One of the interesting aspects of decoding the human genome is that the scientists performed the decoding on only a single set of 23 chromosomes as opposed to 23 pair of chromosomes which we all have. To completely decode or sequence the human genome, researchers used a special tumor that develops an egg with only one set of 23 chromosomes as opposed to 23 pair. As newer technologies come on board, truly complete genome sequencing may be more straight forward and rapid. Soon decoding the entire human genome will not be news at all.