Its no accident that off-spring resemble their parents. Deoxyribonucleic acid or DNA, located within each cell nucleus is a special chemical, that determines our genetic inheritance in a very orderly way. Under the microscope DNA looks like a mass of tangled threads which consist of tiny subunits called genes. Genes carry instructions, sometimes called the blueprint of life, for various characters like hair color, height, eye color. Our genes are received from both mother and father, half from each. Genes instruct our bodies to make proteins - which determines the shape and function of each cell. Each gene controls the production of a particular protein. Genes produce millions of different proteins through different arrangements of just four simple molecules the nucleotides - adenine (A), cytosine (C), thymine (T), and guanine (G). These A,C,T and G's are like letters of the alphabet - their order "spells" out the language of life.
The Human Genome Project (HGP) was proposed in the 1980s and was formally initiated in 1990. Its major aims are to map and determine the chemical sequences of the three billion nucleotide base pairs that comprise the human genome. Completion of the HGP in the projected 15 years will provide a source book for biology and medicine. The Human Genome Diversity Project (HGDP) complements the HGP by examining the genomic variation of the human species, through analysis of DNA from populations, families and individuals worldwide.
There are many different techniques involved in gene screening. With the start of the Human Genome Mapping Project some of these techniques have been altered to speed up the screening process. Examples of these techniques include PCR (polymerize chain reaction), RFLP's (restriction fragment length polymorphism), cloning, and the use of markers for specific genes. One of the biggest inventions that has allowed genetic screening to occur was the invention of PCR (polymerize chain reaction) by Kary Mullis which was patented in 1987. This helps to get large number of copies of a single gene with great speed and ease. RAPD's (Randomly Amplified Polymorphic DNA), GAWTS (Genomic Amplification with Transcript Sequencing) and other techniques are being utilized in the mapping and sequencing of the human genome. GAWTS derived from PCR uses the promoter sequence of a T7 or T3 phage. This is attached to one or both of the PCR primers and is translated into RNA for a single strand template for reverse transcriptase. Advantages of this procedure include amplification of the region of interest thus eliminating the need for purification of the sample after PCR is carried out while compensating for poor quality in the PCR reaction. This along with the ease with which GAWTS lends itself to automation can increase the efficiency at which the screening takes place.
Genetic screening is a process to analyze blood or skin for the systematic search for persons with a particular genotype in a...