Chromosomal Aberations Flashcards
Errors in meitoic chromosome segregation leads to ..
Whole chromosome aneuploidy
Two possible causes of Chromosomal aberration
defects to chromosome segregation and DNA damage repair
Error in DNA damage repair can lead to ..
chromosomal aberrations: structural variation
- affects a large region of DNA, but not entrie chromosome
- can involve one or more chromosomes, and includes copy number variants (CNVs) and rearrangements
Down syndrome (3 copies of chromosome 21) is an example of
whole chromosome aneuploidy, trisomy
when paired chromosomes (meiosis I) or sister chromatids (meiosis II) fail to separate
Nondisjunction
nondisjunction during meiosis can lead to production of … germ cells which is a (deviation from the normal haploid number of chromosomes) which can result in trisomy or monosomy at fertilizaiton
aneuploid
whole chromosome aneuploidy is caused by ..
Nondisjunction events
chromosome analysis test that evaluates the number of a persons chromosome in order to detect abnormalities
- chromosomes are fixed & stained
- from Metaphase cells (bc gm is condensed)
- can detect large aneuploides or rearrangements
Karyotype Analysis
the occurance of one or more extra or missing chromosomes leading to an unbalanced chromosome complement, includes monosomy and trisomy
Aneuploidy
used to describe the absence of one member of a pair of chromosomes
Monosomy
used to describe the presence of an extra chromosome, add 1
ex: down syndrome
Trisomy
Presence of a set of extra chromosomes, adding 23 to 46
Triploidy
The loss of one set of chromosomes, 46-23 = 23
Monoploidy
Monoploidy and Triploidy are NOT considered …
Monosomy and Trisomy are considerered..
Aneuploidy
Most whole chromosome aneuploidies are lethal, what are execptions (5)?
Patau syndrome (trisomy 13) Edwards syndrome (trisomy 18) - result in live birth, few survive after 1 year Down syndrome (trisomy 21) Turner syndrome (XO) (monosomy of X chrome) Klinefelter syndrome (XXY) males w extra X