DNA/Genetic Reports glossary of terms
Developments in genetic testing have brought about a whole new language which can be difficult to understand. Below I have attempted to explain, in simple terms, some of the language you may encounter when going through your DNA report.
AN EXPLANATION AND GLOSSARY OF TERMS
NUTRIGENOMICS: The study of the interaction between nutrients (diet) and genes and genetic expression.
NUTRIGENETICS: Nutrigenetics examines how your body responds to nutrients based on your genetics.
EPIGENETICS: The study of how diet, lifestyle, environment, switches your genes on or off.
GENES: we have approximately 22,000 genes which give the instruction to build an organism. These genes are housed in 23 pairs of Chromosomes.
DNA: Deoxyribonucleic acid (DNA) is our hereditary template.
DNA consists of four building blocks which have a backbone and 4 chemical bases known as Nucleotides. The 4 Nucleotides are:
- Adenine (A)
- Thymine (T)
- Cyotosine (C)
- Guanine (G)
To make a complete DNA molecule, single nucleotides join to make chains that come together as matched pairs and form long double strands. The nucleotides join in complimentary base pairs – A is always joined to T and C is always joined to G. The base pairs are arranged in two long strands that form a spiral called a double helix. We have approximately 3 billion base pairs.
These building blocks function together in larger units called GENES (Genes are made up of DNA). Each gene is a set of instructions for building a specific protein. A gene is the basic physical and functional unit of heredity. We have approximately 22,000 genes and have 2 copies of each gene, one from each parent.
Genes are housed in 23 pairs of CHROMOSOMES. A chromosome is a linear or circular strand of DNA that contains genes.
A complete set of Genes is called a GENOME. A genome is a set of instructions for building an entire organism.
Every person’s genome has the same genes arranged in the same order. The DNA of any two individuals is 99.9% identical. But small variations in the sequences of the base pairs make each person unique.
SNP’S (pronounced SNIPS) – Slight variations in the base pairs can influence the ability of genes to perform their required functions. These variations are known as SNP’S – Single Nucleotide Polymorphisms (SNP’s – pronounced SNIPS).
They can act as biological markers indicating a predisposition towards a behaviour, physical or physiological attribute.
ALLELES: Allele is a shortened from of the word allelomorph (‘other form’). An allele is one of a number of alternative forms of the same point within a gene. There are two possible inherited alleles at a given SNP position, one inherited from each parent.
SNPs tell us the position of the changed bases while the allele refers to a single base within a base pair, at that position. It could be a T allele, which tells us that the base being referred to (within the changed base pair) is thymine. Genotype The resulting two alleles inherited (one from each parent) at a given SN
GENOTYPE: The resulting two alleles inherited (one from each parent) at a given SNP position. It is the genetic make-up of a cell, and organism or an individual usually with reference to a specific characteristic under consideration.
PHENOTYPE: Is the composite of an organisms observable characteristics or traits such as its morphology, development, biochemical or physiological properties, phrenology, behaviour, products of behaviour.
RISK VARIANT: Scientists have identified that a certain risk may be associated with particular alleles
HOMOZYGOTE OR HOMOZYGOUS: e.g CC. An individual has inherited the C alleles from both parents
HETEROZYGOTE OR HETEROZYGOUS: e.g. CT – An individual has inherited the C allele from one parent and the T allele from the other parent
GENE EXPRESSION: The process by which a gets “switched on”