Epigenetics and Imprinting Flashcards
Define epigenetics
The study of changes in organisms caused by modification of gene expression rather than alteration of the genetic code itself.
If a gene is methylated, it becomes…
Inactivated.
Define cell lineage
It is the developmental history of a differentiated cell as traced back to the cell from which it arises.
What are ‘jumping genes’?
They are transposable elements. These are sequences of DNA that jump from one location to another. They are stabilized by methylation.
What are imprinting genes?
Imprinted genes are genes whose expression is determined by the parent that contributed them (inherit only one working copy). Imprinted genes violate the usual rule of inheritance that both alleles in a heterozygote are equally expressed.
Give 2 examples of imprinting genes.
Prader-Willi syndrome (constant hunger and obesity). Angelman (severe mental retardation). Beckwith-Wiedemann syndrome (overgrowth and macrosomia). Silver-Russel syndrome (growth retardation).
Random silencing of one X chromosome for female development is known as…
X chromosome inactivation.
X chromosome inactivation is a method of …
Dosage compensation.
What does EWAS stand for?
An epigenome-wide association study (EWAS) is an examination in different individuals to derive associations between epigenetic variation and a particular identifiable phenotype/trait.
What does DOHAD stand for?
Developmental Origins of Health and Disease. Exposures in development (prenatal/fetal) lead to greater susceptibility to human disease later in life.
Give 2 roles of DNA methylation.
Gene expression regulation. Reprogramming: cell lineage. Genomic stability. Genomic imprinting. X-chromosome inactivation. Human disease.
Name 2 conditions associated with X chromosome inactivation.
Haemophilia. Fragile - X - syndrome. Duchenne muscular dystrophy.
Why is an X-chromosome inactivated in a female body cell?
The level of gene activity produced by a single X chromosome is the normal “dosage” for a human. No need for twice the expression.
What is haemophilia?
An inherited genetic disorder that impairs the body’s ability to make blood clots, a process needed to stop bleeding.
What is Fragile - X - syndrome?
A genetic disorder. Symptoms include mild to moderate intellectual disability. It is typically due to an expansion of the CGG triplet repeat within the Fragile X mental retardation 1 (FMR1) gene on the X chromosome.
