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Towards a healthier world
Deoxyribonucleic acid, or DNA, is the basic and the most important part of living cells. The DNA code carries all the genetic secrets of a human or any other living being. In addition to its role in genetics, the DNA is involved in the division of cells in a body, be they the somatic or general type or the gonadal or reproductive kind.
Thus, DNA makes up the living entity of any cell, as it helps it divide, survive and to pass on the genetic information from one cell to another. DNA is very dynamic in its structure as well as in its functions, yet very complex to be detected and studied.
The detection of the human genome system, however, has led to a whole new world of information on DNA. With the help of latest techniques of discovery and experimentation, new phenomena related to DNA are being formulated.
The Hap Map is just such a project. It is an international initiative aimed at classifying, recognizing and cataloging genetic resemblances and differences among human beings.
About the project
The Hap Map is a project that lists the prevalent genetic variations present in a human being. It defines the nature and science of such modifications or variations and the location of their occurrence on the specific structural regions of DNA.
It also studies the distribution of these variations among different people within various groups of populations. One of the most important functions of this project is to find the genes responsible for affecting the general health and disease conditions of an individual along with their responses to medications and environmental factors.
According to the geneticists working on it, the Hap Map project will study and compare the genetic sequence of different people to find the chromosomal locations where the genetic variations and modifications are shared. The countries collaborating in this regard are Japan, US, UK, Canada, China and Nigeria.
The international project will not utilize the genetic information for developing linkages between specific genetic variants and diseases. However, the project will provide new information on the role of genetic make-up vis-a-vis the risk of contracting particular diseases, their prevention, diagnosis and treatment.
The process
The DNA in the living cells is composed of four chemical entities called nucleotides, adenine (A), thymine (T), cytosine (C) and guanine (G). About six billion of these unite in the form of strings in 23 pairs of chromosomes. These genetic chains carry the information which controls our physical attribute, our ability to catch disease and the defence mechanism of our bodies to deal with harmful conditions. The genetic sequences of many individuals are actually quite similar.
When the chromosomes of two humans are compared, their DNA sequence can be identical for hundreds of bases, with variations occurring in about one for every 1,200 bases. One individual can have adenine at a certain location, while another person may have guanine.
A person may have an extra base at a particular region of bases string or may be missing a sequence of DNA. Every specific bonding site of DNA bases is called an allele and the collection of alleles in a person’s chromosomes is known as a genotype.
The difference in the genetic sequencing and the make-up between different individuals is known as single nucleotide polymorphism or SNPs. About 10 million SNPs are found to be occurring commonly in the human genome. It has been observed that when DNA sequences on a part of chromosome seven from two random individuals are compared, two single nucleotide polymorphisms (SNPs) occur in about 2,200 nucleotides.
The Hap Map project is working to find out the basis for a large portion of the genetic variety in the human types. The SNPs work like references to locate the genes in DNA sequence for the geneticists. For example, a change in the sequence of DNA bases increases the chances of suffering from high blood pressure.
However, researchers still do not know the location of the gene in chromosomes. For overcoming this difficulty, scientists will compare SNPs of people who have high blood pressure with the SNPs of those who do not have it. If a specific SNP is more prevalent among the people with hypertension then it could be taken as a marker to locate and recognize the gene involved in the disease.
Since it will be expensive work to check 10 million common SNPs in a person’s chromosomes, the Hap Map will help geneticists make use of how SNPs and other genetic variations are ordered on chromosomes. Those genetic variations which are near to each other are more likely to be inherited together.
Those people who have an A instead of a G at a specific region in a chromosome can have similar genetic variants at other SNPs in the chromosomal region surrounding A. These locations of associated variants are called haplotypes. These are made in the human genome by the molecular mechanisms of reproduction and by the history of our species.
Due to the modern human development, the frequency of haplotypes differs from one area to another via random chance, natural selection and other genetic mechanisms. Due to this, a particular haplotypes can occur at different frequencies in various populations, mostly among those where the populations are distributed widely and are unlikely to share much DNA through mating.
Uses
Hap Map will help in understanding a number of genetic variants and environmental factors, contributing to the cure of diseases like cancer, stroke, heart disease, diabetes, depression and asthma. It hypothesizes the notion of common disease-common variant.
There are many widely distributed genetic variants that are known to be associated with common health conditions. The Hap Map project will be helpful in gaining more knowledge about the relation between these disorders and our genes.
It will customize the medical treatments according to the patient’s genetic make-up, increasing their effectiveness and decreasing their side effects. Genetic variations contributing to the longevity or resistance can be found and will lead to new therapies with greater benefits.
With all the advantages and widespread future prospects of Hap Map, there are various ethical, legal and social concerns being raised against it. However, researchers have made it clear that no information regarding the identity of donors will be revealed, since the samples will remain anonymous.
However, because each sample is identified as coming from a particular segment of population, stigmatization and discrimination may take place in studies that use the Hap Map. Concerns related to some religious beliefs are also being evaluated. But researchers assure that no drug or commercial products will be formulated as part of the project.
The Hap Map is believed to give remarkable results in controlling and curing many diseases that pose a challenge to humanity. It’s expected that the project will provide beneficial outcomes for all countries, particularly for the participating communities. However, it will take several years before the common man will start feeling the effects of the project.
The writer < sabiha_essa@ yahoo.com > is a student of the Fatima Jinnah Dental College
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