Chromosomal abnormalities information Flashcards
Frequency of chromosomal abnormalities in livebirths
0.6%
Frequency of chromosomal abnormalities in infertility
5%
Frequency of chromosomal abnormalities in first trimester SABs
50-60%
Frequency of chromosomal abnormalities in stillbirths and perinatal deaths
6%
Frequency of balanced translocations
Frequency of unbalanced translocations
balanced: 1/500
unbalanced: 1/2000
Frequency of pericentric inversion
1/100
What percent of all clinically recognized pregnancies end in SAB?
15%
Frequency of chromosomal abberrations in AMA women
1/50
Frequency of chromosomal aberrations in the general population
1/160
Risk of carrying a balanced translocation in the general population
1/500 (0.2%)
Level 1 mosaicism
1 abnormal cell in 1 sample
likely pseudomosaic; not reported
Level 2 mosaicism
> /=2 abnormal cells in one sample
usually considered pseudomosaicism
Level 3 mosaicism
> /= 2 abnormal cells in multiple samples
likely true mosaicism
Which cytogenetics test is best for unbalanced translocation?
aCGH - very high resolution!
Only use FISH if targeted
Which cytogenetics test is best for normal balanced translocations?
Karyotype - you can see the chromosomes themselves
