The Arguments for and against developing genetic fingerprint profile of all members of society.

In the United States, federal bureau of investigations (FBI) has created a national database of genetic information called the National DNA Index system. Some experts fear that this database might be used for unauthorized purposes, such as identifying individuals with stigmatising illnesses such as acquired immunodeficiency syndrome (AIDS)

DNA fingerprinting should be developed, as it is the only definite positive and permanent identification method known today. An example of this is that photographs fade and must be updated. Fingerprints can smear or be difficult to acquire as getting fingerprints from babies or a child is nearly impossible.

Individual genetic fingerprints can be obtained from skin cells, semen and hair.

The process is of 4 stages. Within the genes only 2% of the DNA in genes the rest are introns/ non-coding. Non-coding regions are short sequences of bases, which have a core sequence at the start, that repeats over and over again up to one hundred times. DNA fingerprinting is based on the number of repeats of core sequence. Each individual has 50 to 100 different types of minisatellites.

DNA Fingerprinting:

Extraction: -

Sample of tissues containing cells with a nucleus. In the laboratory the DNA is extracted by shaking the sample in a mixture of water -saturated phenol and chloroform. He proteins precipitate out, leaving pure DNA dissolved in the water layer. The amount of tissue that is required is very small:0. 5 cm³ of blood, 0.005cm³ of semen or one hair root.

Digestion: -

Restriction enzymes are added o the DNA to cut it. These enzymes recognise specific base sequences and specific points, close to but not within minisatellites intact. Producing a number of DNA fragments of different lengths, some containing minisatellites.

Separation/with electrophoresis: -

The DNA fragments are separated according to size by electrophoresis. This involves placing the fragments in wells at one end of a block of agarose gel. An electric current is then passed through the gel. The pieces of DNA carry -ve charges and so move towards the +ve charged electrode. The smaller the fragments the faster they move the larger the slower consequently travelling further through the gel. The fragments are separated into 2 separate bands. The patterns are invisible; a probe is added to show the bands containing the minisattelite. This is a single strand of complementary DNA, which cannot attach to the existing double-strand of DNA. To separate the double stranded DNA the fragments are immersed in alkaline solution. Then a technique called southern blotting used to transfer the single-stranded DNA fragments onto a nylon membrane. By putting a thin sheet of nylon over the gel and covering it with absorbent paper towels. The absorbent paper draws the DNA fragments up into the membrane by capillary action, with positions remaining unchanged. The fragments are fixed to the membrane by UV light.

Hybridisation: -

A radioactive DNA probe, bind onto and reveal the location of a certain type of minisatellite. It involves immersing the nylon membrane in a solution containing radioactive DNA probe. DNA probes consist of a single strand of DNA made up of bases. The radioactive probes bind only to a specific site or locus.

The results are analysed by visual inspection to see if the fingerprints match. If there is a match, an automated scanning system is used to calculate the length of the DNA fragments denoted by the band.

The main argument against genetic fingerprinting is the use of private genetic information. The term means any information about an identifiable individual that is derived from the presence, absence, alteration, or mutation of a gene or genes, or the presence or absence of a specific DNA marker or markers, and which have been obtained: This is the key to the act because it defines the information that is protected by it. This definition recognises that not all-genetic information needs or warrants legal protection, and limits the acts protection to information derived from medical examinations, family histories, or pedigrees.

The argument for genetic fingerprinting is that personal genetic information can tell us what will or is likely to occur in our health in future years, unlike tests which tell us about the chance that we exhibit a characteristic of a condition. It is also used to diagnose inherited disorders in both prenatal and newborn babies. These may include cystic fibrosis, haemophilia and Huntingdon's disease. Developing cures for inherited disorders on the chromosomes depend on the information contained in DNA fingerprints.

Bibliography

http://www.dnalc.org/resources/aboutdnafingerprinting.html

http://encarta.msn.com/find/concise.asp?ti=06F0A000#5

http://gwis2.circ.gwu.edu/~mcdonald/educ180/nih/DNA_why.html

http://www.the-scientist.com/yr1989/may/comm_890529.html

http://www.abc.net.au/rural/news/stories/s146143.htm

New Scientist no.2148 22 Aug 1998 pp.36-39

New Scientist no.2029 11 May 1996 p.7

http://www.biotechnology.gov.au/Community_Issues/References/DNA_Fingerprinting/index.asp