Terms used in research
Long string of genes are arranged into 46 chromosomes – 22 pairs (numbered 1-22) and two sex chromosomes (XX for females and XY for males) in every cell in the human body. One chromosome from each pair comes from the mother and one from the father. When viewed under a microscope, each chromosome looks like two cylinders joined together, with a shorter arm (called the p-arm) and a longer arm (called the q-arm). When stained with a particular die, separate bands are visible, each of which is then numbered. UBE3A is situated in 15q11-13 – that is, Chromosome 15, q-arm, region 11-13.
Once a potential therapeutic has been tested as fully as possible in a mouse model, there comes a point when it must be tested in humans. Phase I trials involve small numbers of people and test that the potential therapeutic is safe and has some measureable efficiency. Phase II trials involve larger numbers of participants. Safety and efficacy is still monitored closely, but a larger testing population allows for statistical analysis of efficacy, ie does the therapeutic work and is it cost effective. More information can be gathered about possible side effects and the best dose to give. If the therapeutic is proved to be as good, or better, than existing products, it moves into Phase III trials. Most products tested never pass the Phase I stage. Thousands of potential new therapeutics may reach Phase I trial, but only one or two will make it through Phase III and from there into use by the general population (as a licensed drug product).
In popular usage, “CRISPR” (pronounced “crisper”) is shorthand for “CRISPR-Cas9.” CRISPRs are specialised stretches of DNA. The protein Cas9 (or “CRISPR-associated”) is an enzyme that acts like a pair of molecular scissors, capable of cutting strands of DNA.
Del+ / Del positive
A shorthand term to describe the 70% of individuals with Angelman Syndrome who have the deletion form of the syndrome, where a large chunk of chromosome 15 (approx. 20 different genes) is missing.
Deoxyribonucleic acid (DNA)
This is a long string of 4 different letters (A, G, T, C) known as bases. The way these bases are arranged forms the genetic code of an individual. Certain combinations of these bases group together to form genes.
A disorder of structure or function in a human, animal, or plant, especially one that produces specific symptoms or that affects a specific location and is not simply a direct result of physical injury.
An illness that disrupts normal physical or mental functions.
This is the protein produce of the UBE3A gene. Its exact function is unknown but it is known to be a housekeeping gene. As the cell uses each of the proteins it makes, these genes are responsible for disposing of any left-over fragments, either by targeting them for degradation or recycling the components into new proteins.
Enzymes are macromolecular biological catalysts. Enzymes accelerate chemical reactions. The molecules upon which enzymes may act are called substrates and the enzyme converts the substrates into different molecules known as products.
Combinations of DNA. Each gene makes a single protein which combine together to make the body work. Most genes work together in pairs, with both the maternal and paternal copies contributing jointly. This means that often, if there is a problem with one copy, the effects are not noticed as the other copy covers for the disruption.
In the fields of molecular biology and genetics, a genome is the genetic material of an organism. It consists of DNA. The genome includes both the genes and the noncoding DNA, as well as mitochondrial DNA and, in plants, chloroplast DNA. The study of the genome is called genomics.
The genetic definition of an individual. In the context of a particular condition, eg Angelman Syndrome, we usually mean the genotype of just UBE3A (eg deletion, mutation, etc).
In a very small percentage of genes, only one of the copies, either maternal or paternal, produces the protein product, the other copy is “switched off”. This is known as imprinting and it is not known why this happens.
A karyotype is an organized profile of a person’s chromosomes. Two chromosomes specify sex, XX for female and XY for male. The rest are arranged in pairs, numbered 1 through 22, from largest to smallest. This arrangement helps scientists quickly identify chromosomal alterations that may result in a genetic disorder.
The use of special strains of mice to study a human disease or condition and how to prevent and treat it.
A mutation is a change in the DNA arrangement. Often, this may only be one base change. Even such a small change can either alter the protein product of the gene, or stop it being made altogether.
The physical characteristics – ie, a phenotype can describe the appearance of the genotype. For example, some individuals with the deletion form [genotype] of AS may have fairer skin and lighter hair [phenotype] than their immediate family members.
An agent or treatment given to a population with a particular condition that can alleviate some symptoms of that condition. This rarely means a total cure.
This is the “Angelman” gene. In the brain, only the maternal gene is “switched on”, the paternal copy is silent. As there is no back-up copy, disruptions to this gene, by any of several mechanisms, lead to a diagnosis of Angelman Syndrome.