DNA as a Biometric Identifier

DNA (deoxyribonucleic acid) is the well-known double helix structure present in every human cell. A DNA sample is used to produce either a DNA fingerprint or a DNA profile. For this study and with the current knowledge on the DNA, it is very important to observe the following points:

-only 2-3% of the DNA sequence represents the known genetic material;

-almost 70% of the sequence is composed of non-coding regions, i.e. we do not know the function of these regions;

-almost 30% of the sequence is composed of non-coding repetitive DNA, and only 1/3 is tandemly repetitive, the rest (2/3) is randomly repetitive.

DNA identification is based on techniques using the non-coding tandemly repetitive DNA regions, i.e. the 10% of the total DNA that bears non-sensitive information.

In general DNA identification is not considered by many a biometric recognition technology,mainly because it is not yet an automated process (it takes some hours
to create a DNA fingerprint). However, because of the accuracy level of the process and because we consider it as a possible future biometric trait we have analysed it further together with the standard biometric technologies.

Technology – state of development

DNA testing is a technique with a very high degree of accuracy. The statistical sampling shows a 1-in-6-billion chance of two people having the same profile (Burgess, 2004). Nevertheless, using DNA techniques it is impossible to distinguish between identical twins (the probability of identical twins is
approximately 1 in 250 or 0.4%)36.

According to Bromba (2004), the accuracy of DNA is considered as lower than the one of the iris or retina recognition. Moreover,the possibility of sample contamination and degradation also impacts the accuracy of the method.

Challenges and limitations

Seven pillars
DNA is present in all human beings(universality) and with the exception of monozygotic twins,it is the most distinct biometric identifier available for human beings. DNA does not change throughout a person’s life; therefore the permanence
of DNA is incontestable. It performs well for the applications where it is currently used,(forensics, paternity tests, etc.) though it would not be suitable for every application.

DNA tests are difficult to circumvent under certain conditions (supervised sample collection with no possibility of data contamination). If sample collection is not supervised however, an impostor could submit anybody’s DNA. We all leave DNA traces wherever we go (a single hair can provide a sample) and so it is impossible to keep DNA samples private.

DNA faces several other challenges. Several hours are required in order to obtain a DNA fingerprint. The public is fairly hostile to DNA usage and storage. Further privacy and security concerns are discussed fully below.
In conclusion, DNA performs well on the aspects of universality, distinctiveness, permanence, performance and resistance to circumvention, while it is weak on collectability and acceptability.

Privacy and Security concerns

DNA collection in the past was regarded as invasive sampling (e.g.finger prick for blood). However, DNA sampling methods have evolved to allow less invasive sampling (e.g. collection with a bucal swab of saliva sample or of epidermal cells with a sticky patch on the forearm). Thus,the new sampling methods are not considered to violate the social expectations for privacy (Quarmby, 2003).

The main problem with DNA is that it includes sensitive information related to genetic and medical aspects of individuals. So any misuse of DNA information can disclose information about: (a) hereditary factors and (b) medical disorders.

A DNA profile however is just a list of numbers so it is non-informative and neutral.In addition, in forensics the selection of DNA markers is performed with the aim to be neutral and endeavours to locate DNA markers away from or between genes rather than being part of gene products.

Hence, DNA markers are not established in order to be associated with any genetic disease. Race and ethnicity are actually cultural,not biological nor scientific, concepts. Nevertheless, DNA can tell a person what parts of the world some of their ancestors came from.

The concern with the DNA sample is that it enables to establish sensitive information related to genetic aspects and this is directly related to security. The two main security problems are the security of DNA system (access rights, use of information only for the overriding purpose),and the implementation of security mechanisms in order to ensure for instance a high level of confidentiality and the security of DNA database (access rights, length of information retention).

It seems essential to define the conditions under which the samples can be banked anonymous/anonymised/coded/identified storage) and to guarantee data protection. So, a quality assurance plan and safety regulations of banking (certification of authorised personal, responsibilities listing, safety measures, etc.) are primordial requirements (Godard et al., 2002).

Applications

Each person has a unique DNA fingerprint and it is the same for every single cell of a person. A DNA fingerprint, unlike a conventional fingerprint cannot be altered by surgery or any other known treatment. Apart from its use in medical applications (e.g. diagnosis of disorders), DNA is widely used for paternity tests, criminal identification and forensics. It is also used in certain cases for personal identification as the following two examples illustrate. In the US, a pack, known as DNA PAK38 (Personal Archival Kit) is sold with the aim of conserving a sample so that an individual can be identified in the case of kidnapping, accidents or natural disaster.

Another US company, ‘Test Symptoms@Home’ sells several productsand services based on DNA. One such product is a personal identification card which exhibits general data, such as name, weight, sex, etc, a fingerprint picture and an extract of DNA profile based on the same loci used by CODIS database.

Despite these examples, commercial applications for DNA are very limited; privacy fears and low user acceptance will undoubtedly be a bottleneck for the use of DNA in large-scale applications.

Future Trends

Progress in DNA testing will come in two areas: current techniques will improve, offering more automation, precision and faster processing times, and new techniques will be developed (e.g. by exploiting the electronic proprieties of DNA). Today the time required for a DNA test is in the order of 4-5 hours. Recent experiments though, cited in the annex, suggest that it may be possible to cut this time by half. Nowadays it is impossible to distinguish identical twins. In future however it may be possible to do so either through technical improvements in current DNA testing or through a different approach. One such alternative is to study the DNA of the micro-organisms each person carries, such as viruses, bacteria, or other parasites (Crow, 2001).

A joint partnership between a US and a Taiwanese company currently exploits DNA technology for security solutions and provides several products based on plant DNA technology for anti-counterfeit or tracking purposes, such as DNA ink with a real-time authentication (DNA test pen) or DNA marker integrated into textile materials. For this study, an interesting application of the DNA ink would be to use it for the authentication of passports or visas. Though this is not a direct use of DNA to identify a human, it is a potentially interesting application.

DNA from plants is easier to study than DNA from animals and humans and likewise DNA from bacteria is easier to study than DNA from plants. From this we may infer two likely future trends. The first is that other types of DNA may supplant human DNA for individual identification (e.g. identification through analysis of the micro-organisms carried by each individual as mentioned above).

The second trend is that that current applications based on plant DNA or on animal DNA are likely to exist in the future for human DNA.

Excerpt from report, Biometrics at the Frontiers: Assessing the Impact on Society, For the European Parliament Committee on Citizens' Freedoms and Rights, Justice and Home Affairs (LIBE) March 2005

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