Genetic imprinting Flashcards
what is androgenesis
initiation of development using only paternal genetic material
what is parthenogenesis
initiation of development using only maternal genetic material
how do you get pathogenesis
retention of second polar body and no fusion of paternal material
what does pathogenesis lead to
ovarian teratomas - oocytes that have completed first or both meiotic divisions
how do you get androgensis
fusion of paternal material and no maternal genetic material
what does andorgenesis lead to
hyadatiform moles - mainly 46XX
proliferation of abnormal trophoblast tissue and create tumour
embryo dies at 6 somite stage
what is genetic imprinting
a mechanism that ensures the functional non-equivalence of the maternal and paternal genomes
what does epigenetic mean
it is not encoded in the dna nucleotide sequence
describe angelman syndrome
facial dysmorphism - prognathism (wide mouth drooling)
microcephaly
seizure disorder
ataxic (puppet children)
what is prader-willi syndrome
infantile hypotonia - can't suppress appetite mental handicap cryptorchidism small hands and feet obesity
what connect angelmans and prader-willi syndrome and what is the difference
both have a deletion in chromosome 15
AMS = mothers copy deleted
PWS = fathers copy deleted
which two syndromes display monallelic expression
prader-willi syndrome and angelman syndrome
how does monoalleic expression happen
DNA methylation (via methyl transferase) at CG sites after DNA synthesis one gene is activated and the other is completely methylated or silenced
why does monoalleic expression happen
foetal growth conflict
mother vs father
mother has IGF2 gene turned off but is turned on in the dad
but if they happen at the same time it produces a normal baby
what is beckwith-weidemann syndrome
fetal overgrowth organomegaly hypoglycaemia asymmetry 11p15 sporadic
