Genomic Development Era 1990-2003

It was a big year in 1990. The first gene therapy had been approved. It was Dr. W. French Anderson that performed the first gene therapies. The very first patient was a four year old girl with a combination of two severe immunodeficiency diseases. The Dr. Anderson and his colleagues used some of the girl’s white blood cells to make a healthy and functioning version of the mutated gene. Once the cells were injected back into the girl, she showed little improvement, and needed injections of the enzyme adenosine deaminase.

One of the biggest moments in history for all of genetics also happened in 1990, The Human Genome Project. A plan devised by the US Department of Energy and the National Institutes of Health was submitted to the US Congress. This part that they submitted was only a five year part of their fifteen year plan to the genome of humans, and of model organisms such as roundworms, yeast, and fruit flies. The Human Genome project was a massive project that was completed in 2003. The plan was to fully map the entire human genome, the largest genome ever mapped, and have it publicly accessible to anyone to use for research purposes. That enabled the field of human genetics to be greatly expanded, and for many discoveries and inventions to be made.

Three years later, 1993, the gene for Huntington’s Disease was discovered. Nancy Wexler, the one who discovered it, had been collecting samples from a family that had a high tendency for Huntington’s Disease since 1979. Those samples provided the information to identify a marker that also inherited whenever a person got Huntington’s. After 10 years of analysis, the marker and the gene responsible for Huntington’s Disease was found on the chromosome 4. The mutation that caused the disease is unlike others. Instead of being a typical substitution or deletion of nucleotides, the same nucleotide was repeated three times. The nucleotide that was repeated three times was CAG. The discovery of the gene that caused Huntington’s Disease enabled gene therapies for it to start to be developed.

Also in 1993, another discovery was made. Victor Ambros discovered micro RNA. The nematode Caenorhabditis elegans has a single that produces 22 different nucleotides for a piece of single-strand DNA. The main that this came by as a surprise is the function that the gene does. The lin 4 gene, the gene that produced these nucleotides, was used to regulate the development of the nematode, which a protein is usually responsible for. These RNA molecules were named microRNA, and were later shown to play a big role in gene expression in all eukaryotic species.

It was already a known fact that 3-5% of breast cancer cases are caused by an inheritance that made the woman more susceptible to it, so that means that there is a gene causing it. Having a gene causing it means that gene therapies can be develop to treat the cancer. The only trick was finding that gene. It was 1994, and Mark Skolnics finally found the gene. The gene was found on chromosome 17. The gene was simply named Breast-Cancer 1 or BRCA1. Only a year later another gene was found on chromosome 13, the gene was named BRCA2.

In 1996, another big step was made in the name of genetics. Dolly the cloned sheep was born. Dolly was the first animal to be cloned from a somatic cell. The process of cloning used had multiple steps. The first step was obtaining the nucleus from the egg cell of Sheep 1, and was replaced with the nucleus from Sheep 2. Then the modified egg is implanted into the uterus of Sheep 3. The egg grows and develops into a genetically identical clone of Sheep 1. Dolly the sheep was the result.

The first eukaryotic organism had it’s genome map completed in 1996. That organism was a common one, baker’s yeast. The sequencing was completed by an international collaboration by the Human Genome Project. Baker’s yeast has over 12 million base pairs throughout the 16 chromosomes of it, around 5500-6000 genes. An enormous number, and a very big achievement.

In 1999 a huge set back for genetic treatments happened. Jesse Gelsinger had died after he received treatment for a disorder that disabled his body from properly breaking down ammonia. Upon further analysis, it was learned that Gelsinger died because his immune system had a very large and exaggerated reaction to the viral carrier. After the FDA investigated the death, gene therapy wasn’t going to see use in human trials for many years.

Also in 1999, nine years after the Human Genome Project was launched, the first chromosome was fully sequenced. That chromosome being chromosome 22. The final count for base pairs ended up being over 33 million.

The fruit fly genome was also sequenced in 1999. Gerald Rubin and his team, supported by Celera Genomics were responsible for completing it. Having this happen is important because the fruit fly was the subject for many studies in the past century, and having it’s complete genome accessible enabled our understanding of how it worked to increase further.

The race for completing the sequence for the human genome was between the public Human Genome Project, and the private company Celera Genomics. The race ended up being a tie, with the two’s genome were still in draft form.

2003 marks the end of this era, an odd year to end at. The reason this era ends in 2003 is due to the human genome being fully sequenced. The accuracy of the map was 99.9%, an extremely difficult task to do. The human genome had over 3 billion base pairs to be sequenced. An interesting coincidence, happened also, 2003 was also the 50th anniversary of the discovery of the DNA double helix shape.


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