Glossary of Terms:


One of the variant sequences of a gene at a particular locus, or location, on a chromosome. Different alleles produce variation in inherited characteristics, such as hair color or blood type. In a person, one form of the allele (the dominant one) may be expressed more than another form (the recessive one). One is inherited from each parent.
Buccal swab
A non-invasive buccal brush or swab that, when rubbed on the inside of the cheek, collects cells for DNA analysis. This is a technique commonly used to collect DNA samples.
Cholesterol is a soft, fat-like, waxy substance found in the bloodstream and in all your body's cells. Cholesterol is normally made by the liver and also supplied in the diet through animal products such as meats, poultry, fish and dairy products. It's an important part of a healthy body because it's used for producing cell membranes and some hormones, insulating nerves and serves other needed bodily functions. But too much cholesterol in the blood is a major risk for coronary heart disease, which leads to heart attack.
Packaged DNA and protein in cells. Human beings have 23 pairs of chromosomes. One-half of each pair is inherited from a parent.
A protein or peptide that serves as a communication signal to cells. Examples are interleukins, interferons, and tumor necrosis factors that facilitate the inflammatory response.
A test which measures the active presence of a disease, a condition, or biomarkers of disease.
DNA (deoxyribonucleic acid)
DNA, the molecule inside the nucleus or core of each of the body’s trillions of cells, that carries genetic instructions for making living organisms. DNA is made up of sequences, or what is referred to as your genetic code. Each gene is the code or recipe for a single protein. Everyone has the same genes – in fact, 99.9% of everyone’s DNA is the same.
Double-helix of the DNA
DNA molecule shows two strands of DNA spiraling around each other like a big ladder twisted into a coil.
DNA sequencing
The process by which the exact order of the base pairs in a segment of DNA is determined. Gene A segment of DNA that contains the information necessary to make a protein.
A functional segment of DNA located in a specific region on a chromosome that directs the formation of a protein.
Gene expression
The process of converting the information encoded in the DNA into RNA (mRNA, tRNA, and rRNA); most genes are transcribed into "messenger" RNA (mRNA) and, ultimately, into a protein product.
Genetic counseling
A short-term educational counseling process for persons and families who have an inherited disease or who are at risk for such a disease. Genetic counseling provides persons with information about their condition and helps them make informed decisions.
Genetic risk assessment
Genetic risk assessment testing is intended to identify common genetic variations that produce varying biochemical responses that are directly involved in the underlying cause of a disease and are associated with adverse disease outcomes. Genetic variations that result in a biochemical imbalance and are associated with adverse clinical outcomes may provide further understanding as to why some people are more prone than others to developing serious chronic diseases and why some people respond to treatments for those diseases differently than others. By identifying these underlying biological mechanisms, preventive interventions can be targeted to help reinstate the biochemical balance which may help prolong health and wellness in these individuals.
The study of inheritance patterns of specific traits.
The sum total of all the genetic information in an organism; its instruction book—the blueprint that directs the development and functioning of human beings and other organisms.
The study of genes and their function.
The genetic makeup of a person, as opposed to the phenotype, which is the physiological manifestation of the genotype and its expression.
Possessing two different copies of a particular gene, e.g., two different alleles, one inherited from each parent; a heterozygous person is also called an allele carrier.
High-density lipoprotein (HDL)
Cholesterol and other fats can't dissolve in the blood. They have to be transported to and from the cells by special carriers called lipoproteins. Cholesterol HDL is known as the "good" cholesterol. The body makes HDL cholesterol for protection. It carries cholesterol away from the arteries. Studies suggest that high levels of HDL cholesterol reduce the risk of heart attack.
In the average man, HDL cholesterol levels range from 40 to 50 mg/dL. In the average woman, they range from 50 to 60 mg/dL. HDL cholesterol that's less than 40 mg/dL is low. Low HDL cholesterol increases the risk for heart disease. Smoking, being overweight and being sedentary can all result in lower HDL cholesterol. The higher the HDL numbers the better (³60mg/dL).
Possessing two identical copies of a particular gene, e.g., two identical alleles, one inherited from each parent.
Human Genome Project
An international research project to map each human gene and to completely sequence human DNA; the goals of the project have expanded to include sequencing the genomes of other organisms and to identifying the products of human genes and their functions.
Actual physical position of a gene or marker on a chromosome, a kind of gene address.
Low-density lipoprotein (LDL)
Cholesterol and other fats can't dissolve in the blood. They have to be transported to and from the cells by special carriers called lipoproteins. Cholesterol LDL is known as the "bad" cholesterol. Too much LDL cholesterol can clog arteries, increasing the risk of heart attack and stroke. The lower LDL cholesterol, the lower the risk. In fact, it’s a better gauge of risk than total blood cholesterol. LDL cholesterol will fall into one of these categories:
Target Less than 100 mg/dL
Near Optimal 100-129 mg/dL
Borderline high 130-159 mg/dL
High 160-189 mg/dL
Very High ³190 mg/dL
A pattern of inherited characteristics, such as physical traits or diseases, that results from the interaction of gene and the environment.
The study of the mechanisms by which bioactive dietary components communicate with the genetic material and how genetic variation affects the interaction between these bioactive dietary components and the health and disease potential of a person.
The study of the effects of bioactive dietary components on the genome, proteome (the sum total of all proteins), and metabolome (the sum of all metabolites) at a global, population level.
Nutritional genomics
A field of study focused on optimizing an individual’s genetic potential through understanding how genetic variations (SNPs) influence molecular pathways and define nutritional needs. Conversely, the field is focused on the influence of nutrition and lifestyle on the molecular expression of genetic variations. Includes nutrigenetics and nutrigenomics.
The observable traits of characteristics of an organism, such as hair color or weight, or the presence or absence of a disease. Phenotypic traits are not necessarily genetic.
Characteristic resulting from the combined action of alleles of more than one gene (eg, heart disease, diabetes, and some cancers). Such characteristics are inherited but they depend on the simultaneous presence of several alleles, which typically results in hereditary patterns that are more complex than those of single gene traits.
A common variation among persons in the sequence of DNA; technically a locus is polymorphic when two or more of the alleles at this locus are present in >1% of the population.
Risk assessment
Testing or identification of risk factors (genetic, environmental, clinical or behavioral) that have been associated with increased susceptibility to a disease, adverse clinical outcome or health condition. Risk assessment does not claim that a person definitely will or will not develop a certain condition or disease. However, when risk factors are present the person is predisposed (increased likelihood) for the disease if he/she does not counteract them. When the non-genetic factors are removed or controlled that individual will have a better chance for long-term health.
Signal transduction
Process by which chemical or physical messages are communicated between the surface of a cell and its interior in a step-wise manner that results in a response by the cell.
Single gene disorder
An inherited condition caused by a mutant allele at a single locus in the DNA; such a trait is monogenic (eg, Duchenne muscular dystrophy and sickle cell disease).
Single nucleotide polymorphisms (SNP)
Pronounced “snip”. A variation in a single DNA nucleotide or code (recipe) for a protein. Most of the variation in people is due to SNPs There are millions of these in humans. However, only certain SNPs are functional, i.e., associated with a difference in molecular function significant enough to effect clinical measurements and risk of disease. Numbers are used to identify the chromosomal locations of SNPs and hetero – or homozygosity.
Total blood cholesterol
High cholesterol is a leading risk factor for heart disease. When there is too much cholesterol in your blood, cholesterol and other substances form plaques in the walls of your arteries. Over time, plaque causes "hardening of the arteries" so that arteries become narrowed and blood flow to the heart is slowed down. The blood carries oxygen to the heart, and if enough blood and oxygen cannot reach the heart, an individual may suffer chest pain. If the blood supply to a portion of the heart is completely cut off by a blockage, the result is a heart attack. Heart attacks most commonly occur when plaques become fragile and rupture. Then blood clots are formed and can completely cut off blood supply to a portion of the heart. High total cholesterol has no symptoms until a blockage occurs that can result in a heart attack if not corrected. In general, people who have a total cholesterol level of 240 mg/dL have twice the risk of coronary heart disease as people whose cholesterol level is 200 mg/dL. Total blood cholesterol will fall into one of these categories:
Desirable – Less than 200 mg/dL
Borderline high risk – 200-239 mg/dL
High risk – 240 mg/dL and over
A characteristic associated with a gene that can be quantified or described, such as eye color, flower color, height, intelligence, or the presence/absence of an enzyme.
A change in DNA. Variations are often harmful, causing irreversible diseases, such as Huntington’s Chorea. However, some variations may not have an effect on living organisms; while others confer beneficial effects.


American Heart Association.

National Human Genome Research Institute of the National Institutes of Health. Talking glossary of genetic terms. (

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