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Genetic definitions
What is DNA?
Deoxyribonucleic acid (‘DNA’) is a long complex molecule that holds all the information required for making proteins that help maintain an organism. A gene is a segment of DNA that influences both the physical appearance and the internal functions of the body. They provide instructions to encode the proteins that build and maintain an organism.
What is a gene?
A gene is a segment of DNA that influences both the physical appearance and the internal functions of the body. They provide instructions to encode proteins to build and maintain an organism. Most people have the same genes, however; a small number of genes vary between individuals making them unique.
What is polymorphism?
A genetic polymorphism refers to a particular DNA sequence that involves two or more alleles or discontinuous genotypes in a population.
Most polymorphisms hold variations at a single base pair of the DNA. Single nucleotide polymorphism (SNP, pronounced “snips”) refers to differences of nucleotides in a certain stretch of DNA. For example, the replacement of thymine (T) with the nucleotide cytosine (C).
What is a rs number?
The ‘rs’ stands for the ID number used by databases and researchers to identify the location of a specific SNP.
What is an allele/genetic variant?
An allele refers to a variant form of a gene. Humans inherit two alleles (one from each parent) for each gene. The combination of these alleles represents an individual’s genotype.
Difference between homozygous and heterozygous
A person carrying two identical alleles of a specific gene is called homozygous whereas heterozygous refers to a person carrying different alleles of a specific gene.
Genetic predisposition or genetic susceptibility
Genetic predisposition refers to the susceptibility of an individual to develop a particular disease due to inherited genes. A genetic predisposition means a person carries at least one risk variant of a gene and it can influence an individual’s phenotype under environmental conditions.
