Biomedical subjects

J Benet

Publications and source records attributed to J Benet.

57 records · Page 4Linked to original sources

PubMedDate not supplied

Preimplantation genetic screening and human implantation.

In recent years, preimplantation genetic screening (PGS) has been used and recommended to increase the implantation rate in older women or in couples with previous assisted reproduction (ART) failures, to try to increase pregnancy rates in couples with recurrent abortions, to prevent the transmission of chromosome anomalies to the offspring of carriers of balanced chromosomal rearrangements, or even to try to decrease the incidence of trisomic births in older women. So far, PGS has contributed to increase the implantation rate in older women; however, the rate of clinical pregnancies has not increased, either in older women or in couples with previous ART failures. In couples with recurrent abortions, the pregnancy rate seems to increase, but only when the woman is young (< or =35). In carriers of balanced reorganizations, the prognosis is poor. Attempts to decrease the birth of trisomic children to older women are difficult to evaluate. This absence of relevant results is not related to the technique itself, which is quite safe, but to other still largely unknown factors.

Abortion, Habitual↗

PubMedDate not supplied

Cytogenetic analysis of sperm chromosomes and sperm nuclei in a male heterozygous for a reciprocal translocation t(5;7)(q21;q32) by in situ hybridisation.

We have studied the meiotic segregation of a reciprocal translocation t(5;7)(q21;q32) in a male carrier, using the human sperm-hamster oocyte fusion technique and the whole chromosome painting. A total of 296 sperm complements were analysed by dual chromosome painting. The frequencies of alternate, adjacent-1, adjacent-2 and 3:1 segregation were 49.7%, 32.4%, 16.2% and 1.7% respectively. Aneuploidy frequencies for chromosomes not involved in the translocation were determined by FISH on decondensed sperm heads using probes from chromosomes X, Y, 6, 18 and 21. A total of 20,118 spermatozoa was analysed, 10,201 by two-colour FISH (probes for chromosomes 6 and 21) and 9917 by three-colour FISH (probes for chromosomes X, Y, and 18). There was no evidence of an interchromosomal effect, since disomy frequencies were within the range of normal controls.

Animals↗

PubMedDate not supplied

PGD in female carriers of balanced Robertsonian and reciprocal translocations by first polar body analysis.

Preimplantation genetic diagnosis (PGD) using the first polar body (1PB) is a modality of PGD that can be used when the woman is the carrier of a genetic disease or of a balanced chromosomal reorganization. PGD using 1PB biopsy in carriers of balanced chromosome reorganizations has not become generalized. Here, we describe our experience based on the analysis of unfertilized or fresh, non-inseminated control oocytes, by fixing separately the 1PB and the corresponding oocyte, and on the study of six clinical cases of PGD using 1PB biopsy (four Robertsonian translocations and two reciprocal translocations). In fresh oocytes, the chromosome morphology of the 1PB was well preserved, and the results were always concordant for each oocyte-1PB pair. This indicates that the 1PB can be reliably used for the diagnosis of chromosome reorganizations. In these studies the technical problems encountered when performing PGD using 1PB biopsies for chromosome studies are also addressed. Three different strategies of 1PB biopsy (laser beam, partial zona dissection and acid Tyrode's) and two different protocols (intracytoplasmic sperm injection before or after 1PB biopsy) and their effect on the percentage of oocytes diagnosed and the fertilization rate, are discussed. In reciprocal translocation cases, published in the literature or studied by us, in which at least nine oocytes had been diagnosed, a correlation has been found between the frequency of nondisjunction observed and the theoretical recombination rate. To date, PGD by 1PB analysis alone or combined with blastomere biopsies in female carriers of chromosomal rearrangements has been used in 18 cases, with a further six cases reported here. A total of 325 cumulus-oocyte complexes have been obtained, of which 294 were biopsied and 224 were diagnosed. A total of 52 embryos was transferred, 19 of which implanted and 17 produced full-term pregnancies.

Adult↗