DNA database

Key takeaways

DNA database belongs to biology; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect DNA database to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of DNA database from memory before moving on to harder problems.

Reference excerpt

A DNA database or DNA databank is a database of DNA profiles which can be used in the analysis of genetic diseases, genetic fingerprinting for criminology, or genetic genealogy. DNA databases may be public or private, the largest ones being national DNA databases. DNA databases are often employed in forensic investigations. When a match is made from a national DNA database to link a crime scene to a person whose DNA profile is stored on a database, that link is often referred to as a cold hit. A cold hit is of particular value in linking a specific person to a crime scene, but is of less evidential value than a DNA match made without the use of a DNA database. Research shows that DNA databases of criminal offenders reduce crime rates. Whether larger databases actually weaken match evidence has been debated. Stockmarr argued that searching a database increases the chance of coincidental matches, while Balding maintained that the evidence stays just as strong regardless of how the search was done. Recent analysis suggests both were partly right: traditional DNA profiling operates in a regime where false matches are so rare that database size barely matters, but threshold-based screening systems—which flag individuals matching some number of attributes rather than requiring an exact match—operate in a different regime where false alerts become statistically inevitable as populations grow.

Types

Forensic A forensic database is a centralized DNA database for storing DNA profiles of individuals that enables searching and comparing of DNA samples collected from a crime scene against stored profiles. The most important function of the forensic database is to produce matches between the suspected individual and crime scene bio-markers, and then provides evidence to support criminal investigations, and also leads to identify potential suspects in the criminal investigation. Majority of the National DNA databases are used for forensic purposes. The Interpol DNA database is used in criminal investigations. Interpol maintains an automated DNA database called DNA Gateway that contains DNA profiles submitted by member countries collected from crime scenes, missing persons, and unidentified bodies. The DNA Gateway was established in 2002, and at the end of 2013, it had more than 140,000 DNA profiles from 69 member countries. Unlike other DNA databases, DNA Gateway is only used for information sharing and comparison, it does not link a DNA profile to any individual, and the physical or psychological conditions of an individual are not included in the database.

Genealogical A national or forensic DNA database is not available for non-police purposes. DNA profiles can also be used for genealogical purposes, so that a separate genetic genealogy database needs to be created that stores DNA profiles of genealogical DNA test results. GenBank is a public genetic genealogy database that stores genome sequences submitted by many genetic genealogists. Until now, GenBank has contained large number of DNA sequences gained from more than 140,000 registered organizations, and is updated every day to ensure a uniform and comprehensive collection of sequence information. These databases are mainly obtained from individual laboratories or large-scale sequencing projects. The files stored in GenBank are divided into different groups, such as BCT (bacterial), VRL (viruses), PRI (primates)...etc. People can access GenBank from NCBI's retrieval system, and then use “BLAST” function to identify a certain sequence within the GenBank or to find the similarities between two sequences.

Medical A medical DNA database is a DNA database of medically relevant genetic variations. It collects an individual's DNA which can reflect their medical records and lifestyle details. Through recording DNA profiles, scientists may find out the interactions between the genetic environment and occurrence of certain diseases (such as cardiovascular disease or cancer), and thus finding some new drugs or effective treatments in controlling these diseases. It is often collaborated with the National Health Service.

National A national DNA database is a DNA database maintained by the government for storing DNA profiles of its population. Each DNA profile based on PCR uses STR (Short Tandem Repeats) analysis. They are generally used for forensic purposes, including searching and matching DNA profiles of potential criminal suspects. In 2009 Interpol reported 54 police national DNA databases in the world and 26 more countries planned to start one. In Europe Interpol reported there were 31 national DNA databases and six more planned. The European Network of Forensic Science Institutes (ENFSI) DNA working group made 33 recommendations in 2014 for DNA database management and guidelines for auditing DNA databases. Other countries have adopted privately developed DNA databases, such as Qatar. Typically, a tiny subset of the individual's genome is sampled from 13 or 16 regions that have high individuation.

… excerpt ends here. Continue reading the full article.

Worked examples

Example 1 — a first encounter with DNA database

Start with the simplest possible case. Write down what DNA database claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In biology, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to DNA database before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about DNA database ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of DNA database

In research: DNA database appears in biology research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses DNA database in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: DNA database is common in secondary-school and first-year university syllabi. It links to neighbouring topics Biological databases, Forensic databases, Forensic genetics, so understanding it makes those chapters shorter.
In everyday life: Look for DNA database outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

How to study DNA database in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what DNA database means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain DNA database out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is DNA database in simple terms?

A DNA database or DNA databank is a database of DNA profiles which can be used in the analysis of genetic diseases, genetic fingerprinting for criminology, or genetic genealogy. DNA databases may be public or private, the largest ones being national DNA databases.

Why does DNA database matter?

Because it connects several biology ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study DNA database?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on DNA database.