mathematics

Low copy number

Low copy number is a mathematics topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Low copy number rather than just read about it. In short: Low Copy Number (LCN) is a DNA profiling technique developed by the UK Forensic Science Service (FSS) which has been in use since 1999. In the United Kingdom use of the technique was suspended between 21 December 2007 and 14 January 2008 while the Crown Prosecution Service conducted a review into its use – this suspension has now been lifted.

Key takeaways

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

Reference excerpt

Low Copy Number (LCN) is a DNA profiling technique developed by the UK Forensic Science Service (FSS) which has been in use since 1999. In the United Kingdom use of the technique was suspended between 21 December 2007 and 14 January 2008 while the Crown Prosecution Service conducted a review into its use – this suspension has now been lifted. LCN is an extension of Second Generation Multiplex Plus (SGM Plus) profiling technique. It is a more sensitive technique because it involves a greater amount of copying via polymerase chain reaction (PCR) from a smaller amount of starting material, meaning that a profile can be obtained from only a few cells, which may be as small as a millionth the size of a grain of salt, and amount to just a few cells of skin or sweat left from a fingerprint.

Advantages LCN evidence has allowed convictions to be made in several cold cases. For example, Mark Henson was convicted of rape in 2005, 10 years after the crime was committed, from re-analysis of a microscope slide. In 1981, evidence was deliberately kept after the rape and murder of 14-year-old Marion Crofts in Aldershot. In 1999, a DNA profile was obtained from this using LCN. This was continually checked against the UK National DNA Database for the next two years, until a match was eventually found for Tony Jasinskyj after he was arrested for another crime. He was eventually given a life sentence in 2002. In 2010 the technique was only used in a few countries: the UK, the Netherlands, Poland and New Zealand.

Criticism It has been used in more than 21,000 serious crime cases in the UK and internationally, particularly in "cold" cases. A FSS spokesman said: "LCN DNA analysis is only carried out by the most-experienced DNA scientists, who have undergone special additional training and testing in this area of casework." However, the technique came under attack from the Judge during the trial of Sean Hoey – who was eventually cleared of involvement in the Omagh Bombing. One of the criticisms the judge leveled at LCN was that although the FSS had internally validated and published scientific papers on the technique, there was an alleged lack of external validation by the wider scientific community. Following the Judge's ruling, the use of the technique was suspended in the UK, pending a review by the Crown Prosecution Service. This review was completed and the suspension lifted on the January 14, 2008 with the CPS stating that it had not seen anything to suggest that any current problems exist with LCN.

See also Batman rapist – unidentified British serial rapist whose DNA is known thanks to the low copy number technique

Notes

References Science Behind the Technique, FSS Case closed, The Guardian, January 16, 2008 Statement of Dan E. Krane in the case of R. v. Sean Hoey, October 24, 2006

Worked examples

Example 1 — a first encounter with Low copy number

Start with the simplest possible case. Write down what Low copy number claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In mathematics, 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 Low copy number 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 Low copy number 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 Low copy number

In research: Low copy number appears in mathematics 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 Low copy number 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: Low copy number is common in secondary-school and first-year university syllabi. It links to neighbouring topics DNA profiling techniques, Laboratory techniques, Population genetics in the United Kingdom, so understanding it makes those chapters shorter.
In everyday life: Look for Low copy number 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.

Ask Teacher Smith questions about this articleOpens your AI tutor with a question about “Low copy number” →

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study Low copy number in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Low copy number 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 Low copy number out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Low copy number in simple terms?

Why does Low copy number matter?

Because it connects several mathematics 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 Low copy number?

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 Low copy number.