Genetics 4 Flashcards
what are cytogenetic disorders?
-alterations in the number or structure of chromosomes (affects autosomes or sex chromosomes)
euploid
multiple of the haploid number (n)
polyploid
3n and 4n, spontaneous abortion
aneuploid
not an exact multiple of n
3 types of structural abnormalities that can occur
breakage, loss, rearrangement, translocation, isochromosomes, deletion, inversions, a ring chromosome
translocation
transfer of a part of 1 chromosome to another chromosome, reciprocal
isochromosomes
centromere divides horizontally resulting in 2 short arms only or 2 long arms only
deletion
loss of a portion of a chromosome
inversions
2 interstitial breaks in a chromosome with inversion (turnaround) and reconnection
a ring chromosome
loss of distal segments and a reconnection of the exposed ends to form a ring
sex chromosome disorders
produce subtle abnormalities (imbalances of sex chromosomes more tolerated than autosomes)
trisomy 21 (Down Syndrome)
47 chromosomes- 1 extra
- correlates to maternal age
- translocation of long arm of chromosome 21
trisomy 18
(edwards syndrome)
trisomy 13
(patau syndrome)
microphthalmia
klinefelter syndrome
male hypogonadism that develops when there are at least two X chromosomes and one or more Y chromosomes
