DNA fingerprinting is a laboratory technique used to establish a link between biological evidence and a suspect in a criminal investigation. A DNA sample taken from a crime scene is compared to a DNA sample from a suspect. If the two DNA profiles are a match, then the evidence came from that suspect. Conversely, if the two DNA profiles do not match, then the evidence may not have come from the suspect. Fingerprints of DNA are also used to establish paternity.
The DNA profile (also called DNA fingerprint, DNA test or DNA typing) is a forensic technique used to identify individuals by characteristics of their DNA. A DNA profile is a small set of DNA variations that is very likely to be different in all unrelated individuals, making it as unique to individuals as fingerprinting (hence the alternative name for the technique). The DNA profile should not be confused with complete genome sequencing. Used for the first time in 1984, DNA analysis is used, for example, in kinship and criminal investigation tests, to identify a person or place a person at a crime scene, techniques that are now used globally in science Forensics to facilitate the work of police detectives and help clarify paternity and immigration disputes. DNA fingerprints have also been widely used in the study of animal and floral populations and have revolutionized the fields of zoology, botany and agriculture.
Although 99.9% of the human DNA sequences are the same in each person, enough of the DNA is different that it is possible to distinguish one individual from another, unless they are monozygotic ("identical") twins. The DNA profile uses repetitive ("repeated") sequences that are highly variable, called variable number tandem repeats (VNTRs), in particular short tandem repeats (STRs), also known as microsatellites and minisatellites. VNTR loci are very similar among closely related individuals but are so variable that unrelated individuals are very unlikely to have the same VNTRs.
The modern DNA profiling process was developed in 1984 by Sir Alec Jeffreys while working at the Department of Genetics at the University of Leicester.
Developed by Professor of Genetics Sir Alec Jeffreys, the process begins with a sample of an individual's DNA (usually called a "reference sample"). A common method for collecting a reference sample is the use of a buccal swab, which is easy, non-invasive and inexpensive. When this is not available (for example, because a court order is needed but can not be obtained), other methods may be required to collect a blood sample, saliva, semen, vaginal lubrication, or other suitable fluid or tissue from personal items. Teeth, razor) or stored samples (eg, sperm or biopsy tissue). Samples obtained from blood relatives (related by birth rather than marriage) may provide an indication of an individual's profile, as well as human remains that had previously been outlined.
Next, a reference sample is analyzed to create the individual's DNA profile using one of several techniques, discussed below. The DNA profile is then compared to another sample to determine if there is a genetic match.
DNA fingerprint
• Fingerprints of DNA were invented in 1984 by Professor Sir Alec Jeffreys after they realized that they could detect variations in human DNA in the form of these minisatellites.
• DNA fingerprinting is a technique that simultaneously detects large numbers of minisatellites in the genome to produce a unique pattern for an individual. This is a DNA fingerprint.
• The likelihood of having two people with the same DNA fingerprint that are not identical twins is very small.