When you receive test results from a DNA testing service, the last thing you want is to be faced with confusing words and DNA jargon. If you’re not familiar with biology, the world of Genetics can be full of acronyms and long-winded explanations, along with a few difficult-to-pronounce names. The following guide may help you to understand some of the science behind available DNA tests, as you learn more about the genes that make you, you!
What’s DNA?
DNA is the language your body’s instruction manual – your genome – is written in. Most DNA is stored in the centre, or nucleus of our cells, but a small amount can also be found in a part of the cell called the Mitochondria.
DNA is short for “deoxyribonucleic acid” (one for your next trivia quiz!) and is present in every human cell and almost every other organism on the planet. These instructions – our DNA – are “written” using a string of molecules called nucleotides. This may sound complex, but the DNA “alphabet” is actually very simple. It uses just 4 letters – A, C, G and T – representing the four molecules – adenine (A), cytosine (C), guanine (G), and thymine (T) – that identify each nucleotide. You can think of each of these nucleotides as a letter in your instruction manual.
3 of these nucleotides encode 1 amino acid, for example cytosine (C), adenine (A) and cytosine (C) encodes Histidine. The amino acids are the building blocks of proteins and each one forms a word, for example “CAC” would encode the word for Histidine, in your instruction manual. That’s three letters (or nucleotides) per word (or amino acid).
What’s your genome?
The entire content of human DNA is described as the genome. You can think of your genome as the instruction manual the enables you to function. It’s stored in each cell in your body and contains all the information needed to make, run, and repair you.
What’s a gene?
So, we have our genome instruction manual with its amino acid words and as with all good books, the words aren’t just arranged randomly; they’re formed in patterns that make grammatical sense and convey information. The same is true with our DNA, where a specific sequence of amino acids (or words) will encode a gene (or page in our manual).
Each gene (or page) contains enough DNA for cells to create a single protein or RNA from the amino acids (or words on the page). These proteins are essential for us to function, grow and repair.
What’s a chromosome?
There’s a lot of DNA in the human body, 10 billion miles to be exact! This means 6 feet of DNA per cell, so it has to be packaged efficiently. In order to get it all into one cell, our DNA is tightly packed into 23 pairs of chromosomes. The chromosomes are like the chapters in our instruction manual. Each chromosome (or chapter) has 2 sets of DNA – one from each parent and it’s this that looks like the double helix (twisted ladder) image you see every time there’s a mention of DNA!
So, what’s the difference between a gene and a genome?
To help you get your head around DNA terminology it’s good to know the difference between similar sounding terms! In basic terms, a gene contains enough DNA information for the cell to make a single protein. A genome, on the other hand, contains the sum total of your DNA.
What are SNPs in the world of DNA terminology?
SNP (pronounced “snip”) stands for single nucleotide polymorphisms. A SNP is when a single nucleotide (or letter) in the genome (or instruction manual) is missed, added, or substituted for another and varies between people. It’s a bit like variations in the copywriting of the instruction manual. DNA has a specific script of reference (called a reference genome). During replication, copywriting variations occur, which alter the instructions and causes differences in how the proteins (formed from the amino acids (or words) and genes (or pages in our instruction manual) are made, or not made at all.
Through years of research, geneticists have established that these SNPs are associated with many traits and aspects of our health and wellbeing. Therefore, they can be used to indicate possible futures. It’s important to note, these traits are predictions and aren’t certainties. They’re based on decades of genetic research and only suggest a probability of something happening. When you get your DNA test results, you may find there are SNPs and associated traits that seem to contradict each other. For example, one might indicate you have increased sensitivity to saturated fats, whilst another might indicate a typical sensitivity.
What is an allele?
In DNA testing terminology, an allele refers to two or more (perhaps even more) versions of a single gene. You’ll have inherited one allele from each gene, from each of your parents. The combination of alleles you inherit may affect how strongly you see a certain trait relating to that gene. Some combinations may contribute to a positive effect on a trait, such as being able to build muscle. However, some combinations of alleles may not have such a positive effect, for instance they may lead to you being more likely to be deficient in certain vitamins. If this is the case, you may wish to take action, for example by taking the recommended dose of supplements or changing your diet, if possible, to increase your intake of certain vitamins you may be deficient in.
What does genotype mean?
The term genotype can mean two different things (we know it’s things like this in DNA jargon that can be confusing but hopefully the next bit clears this up for you!) Firstly, genotype can refer to your complete collection of genes i.e. your genetic identity, and secondly, it can refer simply to the two alleles inherited for particular gene.
What is nutrigenetics?
Our DNA and genes can tell us a great deal about ourselves; nutrigenetics is defined as “the science that studies the effect of genetic variation on dietary response.” It tries to understand how the variations in our genes can impact how we react to the food and nutrients we eat. It forms a strong part of personalised nutrition, where you cater specifically to your body’s unique needs.
What is nutrigenomics?
Nutrigenomics looks at the relationship between our diet and our gene expression. It’s thought this research could help prevent diet-related common diseases including heart disease and diabetes. Some experts also anticipate that nutrigenomics may help people achieve certain health goals such as avoiding allergies or obesity.
Reviewed by:
Dr James Harmsworth King MBBS MPhil PhD Biotechnology & Medical Expert
Dr Brian Fisher MBBCh MBE MSc FRSA Medical Expert
Nutrigenomics, individualism and public health – PubMed (nih.gov)
