Disease gene discovery (or identification): The process of finding new genes that might be causing Parkinson’s or other conditions is called disease gene discovery.

DNA: deoxyribonucleic acid. A molecule that contains the instructions an organism needs to develop, live and reproduce. These instructions are found inside every cell, and are passed down from parents to their children. It is made up of molecules called nucleotides, including the 4 bases adenine (A), thymine (T), guanine (G) and cytosine (C). The order of these bases is what determines DNA's instructions, or genetic code. Genes are made from DNA.

DNA sequencing: The process of determining the order of the bases – adenine, guanine, cytosine and thymine – in a molecule of DNA.

Gene: Genes are the code that determines what the cells in your body produce. They are like the instructions of a recipe. There are approximately 20,000 genes that are spread across 26 pairs of chromosomes. They are made up of DNA, comprising of sequences of bases (ingredients) which are specific molecules made up of particular sugars and protein, and are represented by the letters A, C, T and G. Almost everyone has two copies of each gene, one from their father and one from their mother.

Gene panel: A collection of genes to be sequenced together, which are usually linked by common biological pathways, or known disease associations.

Genetic counselling: Genetic counselling is a service that provides support, information and advice about genetic conditions. It's conducted by healthcare professionals who have received training in the science of human genetics (a genetic counsellor or a clinical geneticist).

Genome: An individual’s complete set of DNA, including all of his/her genes.

Genome Wide Association Study (GWAS): Examination of a genome-wide set of genetic variants in individuals with and without an illness to see if any variant is more common in people with the illness.

Single Nucleotide Variant (SNV) or Single Nucleotide Polymorphism (SNP): The technical name for many genetic variations. A difference in a single DNA building block, a nucleotide. For example, a SNP may replace the nucleotide cytosine (C) with the nucleotide thymine (T) in a certain stretch of DNA.

Pathogenic: Disease-causing.

Phenotype: The set of observable characteristics of an individual as a result of their genotype/environment. This might be normal variation between people or their diseases

Source: FutureLearn course, The Genomics Era, St George’s/University of London.