The New Nation - Internet Edition

Md. Kamruzzaman Ferose

DNA or Deoxyribonucleic Acid is the chemical store house of an individual's genetic material. It is a tiny threadlike molecule that contains all the information required for the life process. It is the hereditary blueprint passed on to us by our parents. It governs the inheritance of all the characteristics of an individual such as, eye color, hair color, stature, bone density, personality, likes, dislikes etc. It is a component of virtually all cells in human body. A Person's DNA is same in each cell and do not change throughout lifetime. Any biological evidence like, blood, saliva, semen, hair, teeth, bone tissue etc. therefore, can serve as a potential source of DNA.

DNA Profiling is a process of extracting and analyzing DNA of a biological sample taken from an individual (e.g. victim, suspect, accused) or from the crime scene. In humans about 99.9% of DNA we inherit from our parents is identical among all individuals and difference exists in only 0.1% DNA. The analytical process generates a digital output, which is called the DNA profile. Except for identical twin, every individual has a unique DNA profile.

Forensic DNA Analysis: Forensic DNA analysis usually consists of comparing DNA extracted from crime scene evidence (e.g. blood stain, weapon, cans, bottles, glasses, cigarette butt, personal items etc.) with DNA extracted from the blood of a suspect or accused. In case of sexual assault, the DNA extracted from the semen sample recovered from the victim is compared with the DNA sample taken from the suspect.

Applications DNA Technology in Criminal Investigation: Forensic science uses techniques developed in DNA research to identify individuals who have committed crimes. DNA from semen, skin, or blood taken from the crime scene can be compared with the DNA of a suspect, and the results can be used in court as evidence.DNA technology has made it possible to identify individuals from traces of biological samples. This remarkable technology provides exclusion as well as positive identification with virtually 100% precision.

Personal identification: Personal identification is particularly useful to solve criminal cases like murder, rape, theft or burglary. In these situations comparison is usually made between the samples recovered from the crime scene/victim with the blood samples taken from the suspect. The use of forensic DNA analysis in criminal cases depends first and foremost on the availability of biological samples from the crime scene.

Paternity test: When carrying out a paternity test the DNA pattern of mother, child and the alleged father is compared. A child inherits half of his/her DNA from each parent. Every STR marker in the child's DNA profile therefore should be present in either the mother or father's profile. It can also be used to settle immigration dispute to establish that individuals are true children/parent/siblings in case of family reunification.

Identity of disaster victims: Personal DNA profiling also allows the identification of victims of plane crash, road accidents, explosions, terrorist attacks or fire disasters. In many cases the body found is either severely burnt or recovered body/body fragments are in an advanced stage of decomposition. It becomes then impossible to find out the identity. In such situations, DNA profiles of their tissue samples are compared with close relatives to confirm the identity.

Inheritance dispute: This type of DNA testing often needed to settle an inheritance dispute. There are two basic approaches to solve these cases. The first is to obtain an autopsy sample of the deceased father and generate the DNA profile. The second is to reconstruct the genotype based on surviving family members.

Social Issues: Despite the many benefits offered by DNA technology, some critics argue that its development should be monitored closely. One fear raised by such critics is that DNA fingerprinting could provide a means for employers to discriminate against members of various ethnic groups. Critics also fear that studies of people's DNA could permit insurance companies to deny health insurance to those people at risk for developing certain diseases. The potential use of DNA technology to alter the genes of embryos is a particularly controversial issue. The use of DNA technology in agriculture has also sparked controversy. Some people question the safety, desirability, and ecological impact of genetically altered crop plants. In addition, animal rights groups have protested against the genetic engineering of farm animals. Despite these and other areas of disagreement, many people agree that DNA technology offers a mixture of benefits and potential hazards. Many experts also agree that an informed public can help assure that DNA technology is used wisely.