Chromosomal Abnormalities Flashcards
Abnormal chromosomes account for at least ____ of spontaneous abortions.
50%
Aneuploidy
extra or missing chromosome
More likely to have an ____ chromosome than a _____ chromosome.
Extra, missing
Trisomy
one extra chromosome
Monosomy
one absent chromosome
Polyploidy
extra chromosome sets
Deletion
part of a chromosome missing
Duplication
part of a chromosome present twice
Translocation
two chromosomes join long arms or exchange parts
Inversion
segment of chromosome reversed
Isochromosome
a chromosome with identical arms
Ring chromosome
a chromosome that forms a ring due to deletions in telomeres, which cause ends to adhere
Triploid (3n)
a polyploidy that has three sets of chromosomes
Nondisjunction
meiotic error that causes aneuploidy
Nondisjunction in meiosis 1 results in…
copies of both homologs in one gamete
Nondisjunction in meiosis 2 results in…
both sister chromatids in one gamete
Mosaic
individual with two chromosomally-distinct cell populations
Trisomies
autosomal aneuploids, there are 3 different kinds
Trisomy 21
down syndrome
-most common among newborns
-distinct facial and physical problems
Trisomy 18
Edwards syndrome
- muscle issues, closed fist, don’t survive
Trisomy 13
Patau syndrome
- distinct feature= eye fusion
-don’t survive past 6 months
______ leads to sex chromosome aneuploids.
nondisjunction
Turner(XO) Syndrome
-45, X
- female
-99% effected in utero will die
-sexual maturity impaired
- can’t visualize in 3D
Triplo-X syndrome
47, XXX
-female
-tallness, menstrual irregularities, and slight impact on intelligence
Klinefelter syndrome
47, XXY
-male
- common cause of male infertility bc of incomplete sexual development
- long limbs, large hands and feet
XXYY syndrome
-male
-AAD, OCD, learning disabilities
-infertile
Jacobs symdrome
47, XYY
-male
-phenotypically normal
-great height, acne, speech and reading disabilities
Deletions are often ___ inherited.
not
Cri-du-chat (cat cry) syndrome
deletion 5p
Duplications often ____ inherited.
not
Large duplications tend to have an ________, while smaller ones _____.
effect, do not
2 types of translocation
Robertsonian and reciprocal
Robertsonian translocation
two homologous acrocentric chromosomes break at the centromere and their long arms fuse
How many chromosomes do translocation carriers have?
45
Translocation down syndrome
5% of down syndrome results from Robertsonian translocation
- one parent must be a translocation carrier
Reciprocal translocation
Two non-homologous chromosomes exchange parts
Inversion example
ABCdefG
ABCfedG
Paracentric inversion
inverted region DOES NOT include centromere
Pericentric inversion
inverted region DOES include centromere
Isochromosomes form when…
centromeres divide along incorrect plane during meiosis
Acrocentric
centromere is really far to one side
