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Inge Liebaers

Publications and source records attributed to Inge Liebaers.

28 records · Page 2Linked to original sources
PubMed2004

An excess of chromosome 1 breakpoints in male infertility.

In a search for potential infertility loci, which might be revealed by clustering of chromosomal breakpoints, we compiled 464 infertile males with a balanced rearrangement from Mendelian Cytogenetics Network database (MCNdb) and compared their karyotypes with those of a Danish nation-wide cohort. We excluded Robertsonian translocations, rearrangements involving sex chromosomes and common variants. We identified 10 autosomal bands, five of which were on chromosome 1, with a large excess of breakpoints in the infertility group. Some of these could potentially harbour a male-specific infertility locus. However, a general excess of breakpoints almost everywhere on chromosome 1 was observed among the infertile males: 26.5 versus 14.5% in the cohort. This excess was observed both for translocation and inversion carriers, especially pericentric inversions, both for published and unpublished cases, and was significantly associated with azoospermia. The largest number of breakpoints was reported in 1q21; FISH mapping of four of these breakpoints revealed that they did not involve the same region at the molecular level. We suggest that chromosome 1 harbours a critical domain whose integrity is essential for male fertility.

Chromosome Aberrations↗
PubMed2004

Expression pattern of the Y-linked PRY gene suggests a function in apoptosis but not in spermatogenesis.

In this study, we aimed at analysing the expression of the PRY (PTPN-13 like on the Y chromosome) gene, located on the Y chromosome, in order to define the function of this gene. Active copies of the PRY gene (PRY1 and PRY2) are located in the AZFb region. PCR amplification of PRY cDNA indicated that the PRY gene is expressed in testicular tissue and ejaculated sperm, but not in Percoll-treated sperm. Furthermore, immunocytochemistry on testicular tissue showed the expression of the PRY gene in a small number of spermatozoa and spermatids. In the ejaculate of the male partner of 18 infertile couples, the PRY protein was found in 1.5-51.2% of spermatozoa and in most of the sperm precursor cells. The percentage of spermatozoa showing DNA fragmentation was also determined in 13 of these samples, by using the TdT (terminal deoxynucleotidyl transferase)-mediated dUDP nick-end labelling (TUNEL) reaction. These data correlated with the percentage of PRY-positive cells. When double labelling for PRY and DNA fragmentation was performed to assess whether PRY-positive cells also show DNA fragmentation, we saw that 27-48% of the PRY-positive spermatozoa were also positive for the TUNEL reaction. The overall data of RNA analysis, immunocytochemistry and the TUNEL reaction indicate that the role of the PRY gene in spermatogenesis can be questioned, but suggest its involvement in apoptosis of spermatids and spermatozoa.

Apoptosis↗
PubMed2003

Methylation imprints of the imprint control region of the SNRPN-gene in human gametes and preimplantation embryos.

Imprinting is an epigenetic mechanism leading to mono-allelic expression of imprinted genes. In order to inherit the differential epigenetic imprints from one generation to the next, these imprints have to be erased in the primordial germ cells and re-established in a sex-specific manner during gametogenesis. The exact timing of the imprint resetting is not yet known and the use of immature gametes in assisted reproductive technologies may therefore lead to abnormal imprinting and related diseases. Imprinting is associated with differential allelic methylation in a CpG-context. We studied the methylation patterns of the imprint control (IC) region of the human SNRPN-gene in human spermatozoa, oocytes in different developmental stages [germinal vesicle (GV), metaphase I and metaphase II oocytes] and in preimplantation embryos using the bisulphite sequencing technique. In the spermatozoa, almost all potential methylation sites were unmethylated whereas mainly methylated patterns were found in the oocytes at different developmental stages. In the embryos, an average methylation pattern of 53% was found indicating that the imprints, which have been set during gametogenesis, are stably maintained in the preimplantation embryo. Our results indicate that the maternal imprints for the IC-region of the human SNRPN-gene are already re-established at the GV stage and that they are not re-established in a late oocyte stage or after fertilization as previously reported. Recent advances in assisted reproductive technologies raise questions concerning safety and the epigenetic risks involved. Our study was the first to check the methylation imprints in human pre-implantation embryos and oocytes at different developmental stages.

Autoantigens↗
PubMed2003

Prenatal genetic testing by amniocentesis appears to result in a lower risk of fetal loss than chorionic villus sampling in singleton pregnancies achieved by intracytoplasmic sperm injection.

OBJECTIVE: To compare pregnancy outcome after prenatal genetic testing by chorionic villus sampling (CVS) or amniocentesis in singleton pregnancies achieved by intracytoplasmic sperm injection (ICSI). DESIGN: Retrospective analysis. SETTING: Tertiary referral center. PATIENT(S): Eight hundred twenty-eight patients with singleton gestations achieved by ICSI. INTERVENTION(S): Midtrimester amniocentesis (685 patients) and first-trimester CVS (143 patients). MAIN OUTCOME MEASURE(S): Fetal loss rate, preterm delivery rate, and proportion of babies born with low or very low birth weight. RESULT(S): A significant difference was observed in fetal loss rate between CVS and amniocentesis (3.7% vs. 0.9%, respectively). On the other hand, a similar preterm delivery rate was present between the two methods (11.2% vs. 12.4%, respectively). No significant difference was observed between amniocentesis and CVS in the proportion of babies with birth weight of either <1,500 g (1.8% vs. 3.8%, respectively) or between 1,500 and 2,500 g (8.2% vs. 4.6%, respectively). CONCLUSION(S): Amniocentesis appears to result in a lower risk of fetal loss as compared with CVS in patients with a singleton pregnancy achieved by ICSI.

Abortion, Spontaneous↗
PubMed2002

Preimplantation genetic diagnosis for Huntington's disease with exclusion testing.

Huntington's disease is an autosomal dominant, late-onset disorder, for which the gene and the causative mutation have been known since 1993. Some at-risk patients choose for presymptomatic testing and can make reproductive choices accordingly. Others however, prefer not to know their carrier status, but may still wish to prevent the birth of a carrier child. For these patients, exclusion testing after prenatal sampling has been an option for many years. A disadvantage of this test is that unaffected pregnancies may be terminated if the parent at risk (50%) has not inherited the grandparental Huntington gene, leading to serious moral and ethical objections. As an alternative, preimplantation genetic diagnosis (PGD) on embryos obtained in vitro may be proposed, after which only embryos free of risk are replaced. Embryos can then be selected, either by the amplification of the CAG repeat in the embryos without communicating results to the patients (ie non-disclosure testing), which brings its own practical and moral problems, or exclusion testing. We describe here the first PGD cycles for exclusion testing for Huntington's disease in five couples. Three couples have had at least one PGD cycle so far. One pregnancy ensued and a healthy female baby was delivered.

Female↗
PubMed2002

Children born after assisted reproductive technology.

Since the birth of Louise Brown in July 1978 and the birth of the first intracytoplasmic sperm injection (ICSI) child in January 1992 many couples with longstanding female-factor or male-factor infertility can be helped to overcome their infertility resulting in a delivery and birth of a child. The final and ultimate goal of all infertility treatments has been to give the large population of infertile couples a chance to fulfil their childwish and experience the happiness of having a healthy child. Major advances have been made in the different treatment protocols for infertility during the last 25 years. It is, however, surprising that only a limited number of studies have been carried out assessing the health of the children born after ART. In this review we shall comment on the limitations of follow-up studies on ART children and we shall review existing data on the outcome of in vitro fertilization (IVF) and ICSI pregnancies. The most important outcome data consist of information on minor and major congenital malformations obtained prenatally or after birth, as well as on the further development of the children.

Chromosome Aberrations↗
PubMed2002

Prenatal testing in ICSI pregnancies: incidence of chromosomal anomalies in 1586 karyotypes and relation to sperm parameters.

BACKGROUND: Prenatal testing was offered in all pregnancies obtained after ICSI with ejaculated or non-ejaculated sperm as part of the evaluation of the safety of ICSI. METHODS: Between 1990 and 2001, a chorionic villus sampling (CVS) or amniocentesis was offered for multiple or singleton pregnancies respectively during a genetic counselling session for all couples applying for ICSI. ICSI was carried out using ejaculated, epididymal or testicular sperm. RESULTS: In total, 1586 ICSI fetuses obtained after fresh embryo transfer were tested by CVS (n = 698) or by amniocentesis (n = 888). Abnormal fetal karyotypes were found in 47 samples [3.0%; 95% confidence interval (CI) 2.2-3.9%]; 25 anomalies (1.6%; 95% CI 1.0-2.3%) were de novo. These were 10 sex chromosomal anomalies and 15 autosomal anomalies [either numerical (n = 8) or structural (n = 7)], and 22 inherited abnormalities (1.4%; 95% CI 0.9-2.1%) (21 balanced, one unbalanced). In 17/22 inherited cases the chromosomal structural defect was inherited from the father. A significantly higher percentage of 2.1% de-novo prenatal chromosomal anomalies was observed for sperm concentrations of <20x10(6) sperm per ml, as compared with 0.24% if the sperm concentration was vertical line 20x10(6) sperm per ml (Fisher's exact test, P = 0.006). No statistical difference in frequency of chromosomal anomalies was observed for lower threshold values of sperm concentration (<1x10(6), <5x10(6), <10x10(6) and <15x10(6)). A statistical difference was observed for motility criteria, but not morphology. Three chromosomal anomalies were found prenatally after use of epididymal or testicular sperm in a total of 94 samples; two (of 83 tested) were from patients with obstructive and one (of nine tested) was from a patient with non-obstructive azoospermia. CONCLUSIONS: A significantly higher rate of de-novo chromosomal anomalies (1.6 versus 0.5% in amniocentesis for a mean maternal age of 33.5 years; P < 0.007) was observed in ICSI offspring, relating mainly to a higher number of sex chromosomal anomalies and partly to a higher number of autosomal structural anomalies. This finding was related to sperm concentration and motility. The significantly higher rate of observed inherited anomalies (1.4 versus 0.3-0.4% in prenatal tests in the general population; P < 0.001) was related to a higher rate of constitutional chromosomal anomalies, mainly in the fathers. The hypothesis of a higher risk of post-zygotic events as a consequence of the ICSI procedure leading to a higher proportion of chromosomal mosaicism was not confirmed in this study. Couples should be informed of the risks of an abnormal result related to sperm quality, and of the risk linked to a prenatal procedure as well as about the relatively benign character of some chromosomal anomalies such as de-novo structural anomalies or sex chromosomal anomalies in order to be able to make a choice for prenatal testing, or not.

Adult↗
PubMed2002

Preimplantation genetic diagnosis for fragile Xa syndrome: difficult but not impossible.

BACKGROUND: In this paper, we review our clinical preimplantation genetic diagnosis (PGD) programme for fragile Xa syndrome, analysing if PGD for these couples is still a valuable option, as it is particularly difficult for two reasons. First, the couples have to be informative (the number of triplet repeats on the healthy FMR-1 allele of the mother has to be different from the number of repeats on the healthy FMR-1 allele of the father) and second, women with a premutation are at increased risk of premature ovarian failure. METHODS: A total of 34 couples attended our genetics department between December 1998 and July 2001, requesting information about PGD for fragile Xa syndrome. RESULTS: Eight couples decided not to go further with the procedure and of the 26 remaining couples, 16 were informative (61.5%). Four couples have so far not started ovarian stimulation, one patient was totally refractive to stimulation and 11 couples have had a total of 19 oocyte retrievals. From these, there have been 13 embryo transfers with a clinical pregnancy rate per embryo transfer of 23%; the implantation rate was 13.6% and the live birth rate per couple was 27.3%. CONCLUSIONS: PGD for fragile Xa is feasible for a number of couples. A pre-PGD work-up should include a determination of the premutation or mutation carrier status, the maternal or paternal origin of the premutation and an estimation of the ovarian reserve of the patient. Fragile Xa premutation carriers should be advised not to postpone reproduction for too long.

Adult↗
PubMed2002

Neonatal data on a cohort of 2889 infants born after ICSI (1991-1999) and of 2995 infants born after IVF (1983-1999).

BACKGROUND: To evaluate the safety of ICSI, this study compared data of IVF and ICSI children by collecting data on neonatal outcome and congenital malformations during pregnancy and at birth. METHODS: The follow-up study included agreement to genetic counselling and eventual prenatal diagnosis, followed by a physical examination of the children after 2 months, after 1 year and after 2 years. 2840 ICSI children (1991-1999) and 2955 IVF children (1983-1999) were liveborn after replacement of fresh embryos. ICSI was carried out using ejaculated, epididymal or testicular sperm. RESULTS: In the two cohorts, similar rates of multiple pregnancies were observed. ICSI and IVF maternal characteristics were comparable for medication taken during pregnancy, pregnancy duration and maternal educational level, whereas maternal age was higher in ICSI and a higher percentage of first pregnancies and first children born was observed in the ICSI mothers. Birthweight, number of neonatal complications, low birthweight, stillbirth rate and perinatal death rate were compared between the ICSI and the IVF groups and were similar for ICSI and IVF. Prematurity was slightly higher in the ICSI children (31.8%) than in the IVF children (29.3%). Very low birthweight was higher in the IVF pregnancies (5.7%) compared with ICSI pregnancies (4.4%). Major malformations (defined as those causing functional impairment or requiring surgical correction), were observed at birth in 3.4% of the ICSI liveborn children and in 3.8% of the IVF children (P = 0.538). Malformation rate in ICSI was not related to sperm origin or sperm quality. The number of stillbirths (born > or =20 weeks of pregnancy) was 1.69% in the ICSI group and 1.31% in the IVF group. Total malformation rate taking into account major malformations in stillborns, in terminations and in liveborns was 4.2% in ICSI and 4.6% in IVF (P = 0.482). CONCLUSIONS: The comparison of ICSI and IVF children taking part in an identical follow-up study did not show any increased risk of major malformations and neonatal complications in the ICSI group.

Child, Preschool↗