R Coco, A Gallo, M Muhlmann, Provenzano s Provenzano s
JBRA Assist. Reprod. 2000; 4 (2):51-59
Received April 19, 2000
Accepted May 15, 2000
Abstract
Balanced chromosomal rearrangements are associated with infertility because carriers produce gametes with chromosomal imbalances, which lead to abnormal conceptions, which can be lethal or give rise to malformed births.To evaluate the segregation of the meiotic quadrivalent and its possible interchromosomal effect. The couple was chosen to enter our Preimplantation Genetic Diagnosis(PGD) program. This couple has a history of four spontaneous abortions, two of them with normal chromosome study.The woman had a normal karyotype and the man 46,XY,t(1;4)(p32;q25).Before accessing the PGD, we decided to study the spermatozoa to analyze the segregation of the quadrivalent with probes, which would later be used in the PGD, and also to evaluate the interchromosomal effect on chromosomes 1, 3, 1, 8, 21 and the sexual ones.The studies were carried out on previously decondensed sperm smears.The following mixtures of probes were used to perform FISH:a)two centromeric probes from chromosomes 1 and 4, and one telomeric 4q; b)Three centromeric chromosomes 1 8, X and Y; c)Two specific loci on chromosomes 1, 3 and 21. Approximately 1,000 spermatozoa were analyzed for each mixture of probes used, recording the segregation patterns of the meiotic quadrivalent with the centromeric probes I and 4 and the telomeric 4q, and the nullisomies, disomy and diploidy with the probes of chromosomes 13, 18, 21 and sex chromosomes. The frequencies of the alternate, adjacent I, adjacent II, and 3:1 segregation patterns were:24.0%, 26.4%, 11.4%, and 38.2%, respectively.The frequencies of aneuploidies of chromosomes 13, 18, 21 and sexual pair were:21.5%, 15.2%, 31.0% and 28.2%, respectively.In addition, a frequency of presumably diploid spermatozoa of 11.2% was found. Taking into account the results obtained in the future PGD, not only the chromosomes involved in the translocation should be studied, but also those corresponding to the most frequent viable aneuploidies, due to the demonstrated interchromosomal effect.
