Psych Genetics Flashcards
describe Rett syndrome
almost exclusively female, regression of speech and motor function after 6-18 most (stereotypic hand movements)
what is the genetic abnormality in Rett
MECP2 mutation- X linked and lethal in males
dysregulation of epigenetic machinery
first tier testing for autism
chromosomal microarray
maybe single gene if indicated (fragile X, MECP2, PTEN)
most common copy number variant in schizo
22q11 (DiGeorge) deletion
define epigenetics
heritable traits not due to genetic sequence variants
role of DNA methylation
transcriptional silencing (=Muted or Missing)
covalent modification of cytosine at CpG dinucleotides
Fragile X genetic abnormality
CGG repeat in FMR1- in a non coding sequence, the triplet repeat is expanded and leads to increased methylation
acetylation of histones does…
makes DNA more Accessible and Active
define a complete mole molar pregnancy
no recognizable fetal tissue- has a full set of chromosomes but all from paternal origin
empty ovum fertilzed by single sperm which replicates or two sperm
define partial mole
triploid or more genome, one parent contributes more
define genomic imprinting
expression of certain gene is regulated in manner specific to parent of origin
result is functionally hemizygous
3 ways imprinting can cause disease
silencing epimutations
deletion/mutation can disrupt active allele
uniparental disomy
define uniparental disomy
inheritance of both copies of chromosome from same parent
heterodisomy vs isodisomy
hetero is two different chromosomes from same parent, iso is two copies of same chromosome
why UPD causes abnormal phenotype
absence of heterozygosity, abnormal expression from disordered imprinting
