The paternal effect of chromosome translocation carriers observed from meiotic segregation in embryos.
BACKGROUND
Human translocation carriers may present alterations in meiosis. Understanding the mechanism of meiotic segregation of reciprocal translocations is important for estimation of the risk of either pregnancy loss or birth defects. The objective of this work was to estimate meiotic segregation rates in preimplantation embryos from preimplantation genetic diagnosis (PGD) cycles of female and male reciprocal translocation carriers.


METHODS
In 20 cycles for 14 couples, PGD was performed on 118 day three embryos using fluorescence in situ hybridization (FISH) with specific probes for each translocation. The meiotic segregation modes and the effect of the paternal origin of translocated carrier were estimated.


RESULTS
Overall, the proportions of alternate segregation for normal or balanced chromosome contents in preimplantation embryos from PGD cycles in reciprocal male and female carriers were not significantly different (35.5 versus 23.8%). However, the frequencies of adjacent-1 and adjacent-2 segregation were lower in embryos from female reciprocal translocation carriers than from male carriers. For male translocations, alternate segregation was the most frequent mode. The proportion of 3:1 segregation was the most frequent in female translocations carriers.


CONCLUSIONS
We report differences in segregation modes in embryos obtained from PGD cycles according to the gender of reciprocal translocation carrier. However, these differences did not affect the proportion of balanced embryos and the take home baby rate. The analysis of the meiotic behaviour of chromosomes and the differences between the meiotic products of female and male for a chromosomal rearrangement could help predict the outcome of PGD for translocation carriers.
Lledó
Belén
B
IB Biotech, Avda. Albufereta, 31, 03016 Alicante, Spain. blledo@institutobernabeu.com
Ortiz
José A
JA
Morales
Ruth
R
Ten
Jorge
J
de la Fuente
Pedro E
PE
García-Ochoa
Carlos
C
Bernabeu
Rafael
R
D001757:Blastomeres / Q000648:ultrastructure*; D020090:Chromosome Segregation / Q000502:physiology*; D004624:Embryo Transfer; D005260:Female; D006580:Genetic Carrier Screening; D006579:Heterozygote; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D007621:Karyotyping; D008297:Male; D008540:Meiosis / Q000502:physiology*; D011247:Pregnancy; D011256:Pregnancy Outcome; D019836:Preimplantation Diagnosis; D012737:Sex Factors; D014178:Translocation, Genetic