monogenic diseases Flashcards
epigenetics and genomic imprinting: explain what is meant by epigenetics; list two specific examples of genomic imprinting disorders, outlining possible mechanisms, clinical features and transmission patterns
epigenetic inheritance definition
transmission of a heritable pattern of gene expression from one cell to its progency that doesn’t involve altering DNA nucleotide sequence
parental origin imprint effect
carried on genome; affects 75 genes; non-mendelian; no change in genetic sequence; epigenetic modification (gene activation)
DNA → transcriptome
DNA → gene → chromosome → genome → transcriptome (all mRNA expressed)
effect of methylation on DNA
inactivates gene (e.g. X-inactivation, imprinting)
parental imprinting
diagram from genetics 3
somatic lineage effect on embryo
maintains inherited set of markings for embryo
germline lineage
epigenetic marks erased and reset (depending on fate of sex of gamete, marking that controls imprinted gene expression is reset in developing gamete)
effect of disorders on chromosome 15
loss of function of specific parental chromosome due to point mutations, chromosomal microdeletions or uniparental disomy
diagnosis of chromosome 15 disorders
use FISH and PCR
chromosome 15 disorders
Prader-Willi syndrome and Angelman syndrome
Prader-Willi syndrome
deletion in paternal chromosome 15 or uniparental disomy (both chromosomes inherited from one parent); obesity and mental impairment; treated with diet restriction and growth hormone development
Angelman syndrome
deletion in maternal chromosome 15 or uniparental disomy (both chromosomes inherited from one parent); development delay, movement disorders
