chromosomal abnormalities Flashcards
numerical abnormalities
aneuploidy and polyploidy
what is aneuploidy?
abnormalities in meiosis, missing a chromosome from pair or has extra chromosome in pair
trisomy
extra chromosome in pair, eg down syndrome trisomy 21
monosomy
turner syndrome - female born with 1 X
what is polyploidy
more than 2 pairs of the same chromosome
structural abnormalities
ring formation, deletions, duplications, inversion, translocation
What are deletions
portion of chromosome is missing, terminal or interstitial
consequences of deletions
unmasking of mutant alleles and insufficient gene products eg cri de chat syndrome
what are inversions
portion broken off , turner upside down and re attached, can be pericentric or paracentric
what causes epilepsy
ring formation abnormality
translocations
portions of chromosome transferred to another
what is robertsonian translocations
entire chromosome attached to another at centromere
what causes schizophrenia
translocation
how does mosaicism occur?
abnormality occurs after conception
