Friday, March 27, 2009
Human Gene prospecting in Iceland
This is an article inspired by a conversation between my father and me. My father, Dr.A.V.S.S.Sambamurty, is a retired Reader in Botany from Sri Venkateswara College, Delhi University. He had written many books on Genetics, his field of research in PhD.
He was explaining a unique phenomenon in Iceland regarding the population's gene structure. I got so interested, wondered at nature and wanted to share the same with all of you.
Caveat: It might get a little technical at certain places, but mostly my father tried keeping it comprehensible by non-botanists, like me. :) A few terms are defined for better understanding of the article in the beginning.
Genome is the complete gene sequence of any living organism. Human genome implies all the genes present on the 24 chromosomes, and their complete sequence upto the nucleotide level.
Four nucleotides are C(cytosine), G(guanine), T(thyamine), A(adenine). These exist as complimentary pairs on the DNA strand. C-G forms one pair and A-T forms the other pair.
Human Genome Project
A little introduction into the human genome project will reflect the importance of the study conducted in Iceland.
The Human Genome project was launched in 1990. The goal of HGP is to map all the 70,000 to 100,000 human genes to construct a detailed physical map of the entire human genome and also to determine the nucleotide sequences of all 24 human chromosomes by the year 2005.
Geneticists all over the world came to form Human Genome Organisation (HUGO). James Watson with Francis Crick discovered double-helix structure of DNA in 1953. He was the first director of this ambitious project which was expected to take nearly two decades to complete and to cost around $3 bn. In 1993, Francis Collins who with Lap-Chee Tsui, led the research teams that identified the cystic fibrosis gene, replaced Watson as the director of HGP.
Benefits of Human Genome Project
The availability of detailed maps and nucleotide sequences of entire genomes of many species allows scientists to perform computer searches for sequences that encode enzymes with desired activities, to isolate these sequences, and to introduce them into the genomes of other species. Scientists have already engineered transgenic plants that are herbicide and insect resistant as well as plants that synthesize antibodies, drugs, enhanced level vitamins and even plastics.
GENE POOL IN ICELAND
An interesting component of the effort to identify human genes with important pharmacological values is taking place in a somewhat unexpected location, the remote island of Iceland, located in the North Atlantic between Greenland and Scandinavia. Because of their history and geographical isolation, the 270,000 people of Iceland provide a unique resource for genetic studies. They are genetically quite homogeneous, descendants of Vikings, who settled on this island more than 1100 years ago. This homogeneity has been enhanced by two genetic bottlenecks during which the population was sharply reduced. During the 15th century, population plummeted from around 70,000 to around 25,000 when bubonic plague ravished the island. During the 1700s, the population dropped below 50,000 because of famine, and disease caused in part by the eruption of the volcano Hekla. Thus, human gene pool of Iceland is much more homogeneous than the gene pools of most other human populations. Such a population is called Endemic Population. In addition, Iceland's national health service has kept superb family medical records since 1915.
Benefits passed on to Iceland
In 1997, Kari Stefansson, a Harvard geneticist, recognised the uniqueness of Iceland's human gene pool and family records. He returned to his homeland to launch a private company, deCODE Genetics, with the goal of identifying human genes that would lead to the development of new pharmaceutical drugs and diagnostic tests. The company's first success was the identification of familial essential tremor gene - , a gene associated with the shakiness in the elderly. In addition, deCODE scientists have made rapid progress in their studies of several other human disorders.
Based on these results deCODE Genetics negotiated a contract with the Swiss pharmaceutical giant, Hoffmann-LaRoche, which will give the Swiss firm exclusive rights to any drugs or diagnostic products resulting from the work of deCODE scientists. However, contract specifies that Hoffmann-LaRoche must provide free of charge all drugs, diagnostic test and other products resulting from this research to the people of Iceland. Therefore, at least in this one case, the people who are providing genetic data and the DNA samples for analysis will personally benefit from the results of research by a private company.
Is it not fascinating to know that a small part on our globe has such homogeneous population with unique genetic history? They have not blended by other genetic populations. Physically, one may not find any thing to observe, but the uniqueness lies at the microscopic level!!