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I Liebaers

Publications and source records attributed to I Liebaers.

At least 127 records · Page 7Linked to original sources
PubMed1994

Birth after preimplantation diagnosis of the cystic fibrosis delta F508 mutation by polymerase chain reaction in human embryos resulting from intracytoplasmic sperm injection with epididymal sperm.

Men with congenital bilateral absence of the vas deferens (CBAVD) have been regarded as presenting a mild form of cystic fibrosis (CF). In this article, we report a case of male-factor infertility, in which both partners are carriers of the delta F508 mutation and the male partner has CBAVD. Microsurgical epididymal sperm aspiration (MESA) was performed to obtain spermatozoa; intracytoplasmic sperm injection (ICSI) was carried out on the oocytes since the motility of the spermatozoa was severely impaired; and embryo biopsy and a polymerase chain reaction (PCR) were carried out for preimplantation diagnosis of the CF delta F508 mutation. Single-blastomere analysis was performed and indicated that two embryos were affected (homozygous delta F508) and three embryos were carriers. After transfer of the latter three embryos, a singleton pregnancy was established. At amniocentesis, the delta F508 carrier status of the fetus with a 46, XY karyotype was confirmed. A healthy boy was born and the presence of vasa deferentia, bilaterally, was confirmed. The CF sweat test was also normal. Successful fertilization can be obtained by combination of MESA and ICSI in patients with CBAVD. Preimplantation diagnosis of CF is indicated. Pregnancy and birth of normal children can ensue in such patients.

Adult↗
PubMed1994

Molecular basis for type 1 antithrombin deficiency: identification of two novel point mutations and evidence for a de novo splice site mutation.

Inherited type 1 antithrombin (AT) deficiency is characterized by a reduction in both immunologically and functionally detectable protein. The disorder is associated with a high risk of thromboembolic disease. We have investigated the molecular basis of type 1 AT deficiency in three unrelated families. We have used the polymerase chain reaction single-strand conformation polymorphism (PCR-SSCP) analysis, followed by direct sequencing of the seven exons and the intron-exon junctions of the AT gene. Two novel point mutations were identified. A T to C single-base substitution was found in codon 421 in exon 6 (nucleotide position 13380), leading to an AT 421 isoleucine to threonine substitution. In another kindred, one of three Cs at nucleotide (nt) positions 5448 to 5450 in exon 3A (codon 151 or 152) was deleted, resulting in a frameshift mutation and predicting premature termination of protein translation at codon 251. In a third family, a previously reported G to A substitution, at nt position 9788 in intron 4, 14 bp in front of exon 5, was found. We have demonstrated the creation of a de novo exon 5 splice site by ectopic transcript analysis of lymphocyte mRNA. In all cases, the affected individuals were heterozygous for the mutation and no variant AT protein was detected.

Adolescent↗
PubMed1994

Antithrombin-Gly 424 Arg: a novel point mutation responsible for type 1 antithrombin deficiency and neonatal thrombosis.

Inherited type 1 antithrombin (AT) III deficiency is characterized by a decrease of immunoreactive and functional protein levels to about 50%. The disorder is associated with a significantly increased risk of thromboembolism. We have investigated the molecular basis of type 1 AT deficiency in a Belgian family. The diagnosis of the disease was primarily made in a newborn girl with unusually severe thrombotic complications. Using the polymerase chain reaction and single-strand conformation polymorphism analysis, followed by direct sequencing of AT gene fragments, we identified a novel point mutation in exon 6. We detected a G to C substitution in the first position of codon 424 leading to a glycine to arginine substitution. The modification at this highly conserved position in the serine protease inhibitor gene family probably leads to an unstable mutant-gene product. The mutation creates a unique restriction site for the enzyme Hha I in exon 6. This change permitted a rapid and accurate screening of the kindred with identification of the molecular defect in five other family members.

Adult↗
PubMed1994

Intracytoplasmic sperm injection.

Intracytoplasmic sperm injection (ICSI) is a promising assisted fertilization technique that may benefit women who have not become pregnant by in-vitro fertilization. ICSI and subzonal insemination (SUZI) were used to treat couples who failed fertilization after standard IVF or who could not be accepted for IVF because too few motile spermatozoa were present in the ejaculate. This paper describes the outcome of 750 consecutive cycles of SUZI and ICSI. Different aspects of these novel assisted fertilization procedures are described: patient management, ovarian stimulation, semen evaluation and treatment, oocyte collection and preparation, SUZI and ICSI techniques, assessment of fertilization and embryo cleavage, outcome of embryo transfers and the evolution of the pregnancies.

Embryo Transfer↗
PubMed1994

Amplification of X- and Y-chromosome-specific regions from single human blastomeres by polymerase chain reaction for sexing of preimplantation embryos.

We describe a polymerase chain reaction (PCR) assay for the simultaneous detection of X and Y chromosomes in human blastomeres. In a first round of PCR, both X- and Y-specific fragments are amplified with primers which are common to both chromosomes and are derived from the X-linked steroid sulphatase gene and the Y-linked pseudogene. In a second round of PCR, fragments specific to each chromosome are generated: both an X and a Y fragment in male embryos and, due to the absence of a Y chromosome, only an X fragment in females. The efficiency and accuracy of this assay are high; it generates no false positive amplification signals and allows sexing in approximately 6 h after embryo biopsy. We therefore believe that it is suitable for gender determination by preimplantation diagnosis for couples at risk for X-linked genetic diseases.

Base Sequence↗
PubMed1994

Prospective follow-up study of 55 children born after subzonal insemination and intracytoplasmic sperm injection.

In 163 couples referred for assisted fertilization, pregnancy was established by subzonal insemination (SUZI), intracytoplasmic sperm injection (ICSI) or a combination of both techniques. These couples agreed to participate in a prospective study that included a prenatal diagnosis and clinical follow-up of the children. No cytogenetic aberrations were observed in 43 children tested. In 23 pregnancies occurring after SUZI, 15 women gave birth to 21 children. After replacement of combined SUZI and ICSI embryos, 10 pregnancies resulted in 8 deliveries with 10 children. Transfer of ICSI embryos led to 130 pregnancies ending in 20 deliveries with 24 children, with many others still ongoing successfully. In total, 55 children have been examined: 29 boys and 26 girls. One child from a singleton pregnancy presented multiple congenital malformations; one twin child presented a quadriparesis. In this observational study on a limited number of children, the incidence of major malformations was not different from the incidence in the general population.

Abnormalities, Multiple↗
PubMed1994

Aberrant splicing of exon 6 in the pyruvate dehydrogenase-E1 alpha mRNA linked to a silent mutation in a large family with Leigh's encephalomyelopathy.

Pyruvate dehydrogenase (PDH)-E1 alpha deficiency has recently been studied at the molecular-genetic level. The gene is situated on the X chromosome. We report on an unusual mutation in a familial E1 alpha deficiency. In fibroblasts, PDH deficiency was diagnosed in a young infant presenting with Leigh's encephalomyelopathy and in a maternal nephew with episodes of "malaises." In the two affected children as well as their mothers we found a silent mutation in exon 6 of the PDH-E1 alpha and an aberrant splicing of exon 6 in some of the cDNA clones. This case emphasizes the need for both genomic and cDNA analysis in cases where a PDH-E1 alpha deficiency is strongly suspected.

Base Sequence↗
PubMed1994

A case of term mors in utero in a chromosome 11p linked long QT syndrome family.

Isolated congenital long QT syndrome is an autosomal dominant disorder characterized by recurrent syncopes, ventricular arrhythmias, or sudden death often accompanied by a prolonged QTc interval on ECG. On the occasion of a pregnancy complicated by an intra-uterine death of a full term baby with prolonged bradycardia a long QT syndrome was diagnosed in the mother. Familial examination revealed a prolonged QTc in her mother, brother and sister, all with positive history of syncopes. DNA linkage analysis was subsequently performed in this family with DNA markers on the short arm of chromosome 11. Four of the children in the family, younger than 5 years, were found to be asymptomatic carriers. Three of them showed a clear QTc prolongation on a 12 lead ECG. Another showed QTc prolongation during Holter monitoring but had a normal basic ECG. Measurement of QTc interval in families affected by the long QT syndrome is helpful but does not always permit an accurate diagnosis. Familial screening with DNA linkage analysis especially in families where a member is affected by the syndrome, can reveal "masked" cases which can further be investigated with Holter or effort ECG. The identification of locus heterogeneity of the long QT syndrome complicates genetic diagnosis. Only prospective studies in more families with long QT syndrome can show the additional diagnostic and prognostic value of DNA linkage.

Adult↗
PubMed1993

Detection of more than 94% cystic fibrosis mutations in a sample of Belgian population and identification of four novel mutations.

We have analysed 194 Belgian CF chromosomes using a variety of techniques: delta F508 was detected by polyacrylamide gel electrophoresis; dot blotting of PCR products was used to identify the mutations G542X, 1717-1 G-->A, and N1303K; molecular defects in exons 2, 3, 4, 5, 6b, 7, 11, 12, 13, 14a, 14b, 17b, 19, 20, and 21 were screened for by DGGE. We identified 17 mutations, which accounted for 94.3% of the Belgian CF chromosomes. Four novel mutations and a novel polymorphism were characterized. The detection of such a high proportion of Belgian CF mutations is important in understanding the functional role of the molecule and in improving prenatal and genetic diagnosis of CF.

Adolescent↗
PubMed1993

Molecular analysis of a patient with hydrops fetalis caused by beta-glucuronidase deficiency, and evidence for additional pseudogenes.

A patient with hydrops fetalis caused by beta-glucuronidase deficiency was found to be homozygous for a C to T transition at nucleotide position 672 in his cDNA. Genomic analysis showed the presence of pseudogenes for the beta-glucuronidase gene. After separation of PCR products of the gene and the pseudogenes it was shown that the patient and his father were heterozygous for the C-T 672 transition and the mother did not carry the mutation.

Base Sequence↗
PubMed1993

Polymerase chain reaction analysis of the cystic fibrosis delta F508 mutation in human blastomeres following oocyte injection of a single sperm from a carrier.

The efficiency of the polymerase chain reaction (PCR) in detecting the cystic fibrosis (CF) delta F508 mutation (which is the most common mutation of CF) was assessed in single human blastomeres. Twenty-one human immature oocytes (germinal-vesicle-stage oocytes) that had been donated for research were matured in vitro and a single spermatozoon from a carrier of the CF delta F508 mutation was injected into the ooplasm. Fourteen embryos were obtained after intracytoplasmic sperm injection (ICSI). PCR analysis was carried out on 70 single blastomeres isolated from these 14 embryos. The results showed that the efficiency of DNA amplification by PCR in single nucleate blastomeres was 94 per cent (59/63). There were no false-positive results since none of the blank samples or the blastomeres without a nucleus showed an amplified signal. We found that nine embryos were homozygous for the unaffected genotype and that four embryos were heterozygous since they contained both the unaffected and the delta F508 genotype. In a four-cell embryo, we observed the homozygous unaffected genotype in one blastomere and a heterozygous delta F508/unaffected genotype in the other three blastomeres.

Blastomeres↗
PubMed1993

Neuropathological findings of a patient with pyruvate dehydrogenase E1 alpha deficiency presenting as a cerebral lactic acidosis.

Neuropathological findings are reported of a 6-month-old female child with a "cerebral" lactic acidosis. A mutation in the pyruvate dehydrogenase (PDH) E1 alpha gene was found. Gross examination of the brain revealed a severe thinning of the cerebral parenchym, a marked hydrocephalus sparing the aqueduct and fourth ventricle, agenesis of the corpus callosum and heterotopic noduli of gray matter in subependymal regions. Microscopical examination showed heterotopic inferior olives, absent pyramids and focal neuroglial overgrowth into meninges. In addition some heterotopia of Purkinje cells and dysplasia of the dentate nuclei were observed. There was a marked vascular proliferation with many thin-walled, congestive vessels in the cerebral and cerebellar white matter, and to a lesser extent in the striatum. To our knowledge these cerebellar and vascular abnormalities have not been reported before in patients with "cerebral" lactic acidosis. The combination of these neuropathological findings might be characteristic for PDH deficiency and more specifically for its E1 alpha subtype. Neuropathological examination could lead to the retrospective diagnosis of PDH E1 alpha deficiency in those cases where biochemical investigations were not or incompletely performed. This may have potential implications for genetic counseling.

Acidosis, Lactic↗
PubMed1993

Efficiency of polymerase chain reaction assay for cystic fibrosis in single human blastomeres according to the presence or absence of nuclei.

OBJECTIVE: To amplify by polymerase chain reaction (PCR) assay the region of the most common mutation of cystic fibrosis (CF) in human blastomeres. DESIGN: Blastomeres were isolated from two- to eight-cell tripronucleate embryos. The nuclear status of blastomeres was recorded by light microscopy (LM) and by fluorescence microscopy after vital labeling with the fluorochrome Hoechst 33342 (H-33342; Sigma, Brussels, Belgium). In each blastomere the region around the delta F508 mutation site was amplified by two PCRs with nested primers. SETTING: Research units of the Centres for Reproductive Medicine and Medical Genetics of the Dutch-speaking Free University of Brussels, Belgium. RESULTS: The presence of a nucleus by LM in 118 of 160 blastomeres was always confirmed by fluorescence microscopy, and in 10 additional blastomeres the nucleus was only visible by fluorescence microscopy. In the PCR assay all blanks were negative and in nucleate blastomeres (assessed by LM) the amplification rate was 96%. After staining with Hoechst dye the percentage of amplification was 71% or 91% if PCR was performed 2 hours or 20 hours after coloration. CONCLUSION: Efficient preimplantation diagnosis for CF on blastomeres requires assessment of nuclear status by LM and vital staining on blastomeres that are anucleate by LM.

Benzimidazoles↗
PubMed1992

Efficiency and accuracy of polymerase-chain-reaction assay for cystic fibrosis allele delta F508 in single cell.

Diagnosis of genetic disorders in the embryo before implantation, though possible by removal of one or two blastomeres at the eight-cell stage, is still experimental because the procedures of gene analysis of DNA from a single cell are not yet reliable enough for clinical application. We have evaluated the efficiency and accuracy of polymerase-chain-reaction (PCR) amplification of a single-copy gene, wild-type or cystic fibrosis delta F508 allele, on single sperm cells from a donor known to be a heterozygous carrier of the delta F508 mutation. DNA from single spermatozoa was decontaminated by restriction-enzyme treatment, then the region around the delta F508 site was amplified by nested PCR. The distribution of the wild-type and mutant alleles (59 [55%] and 48 [45%, respectively]) in the 107 single spermatozoa did not differ from that expected (50% each). 1 sample did not provide an amplified signal. To check that the two alleles would be amplified with equal efficiency when they were both present within a cell, we did PCR for 51 two-sperm samples. Again the distribution did not deviate from that expected (17 [33%] both wild-type; 21 [41%] one wild-type, one delta F508; 13 [26%] both delta F508 vs 25%; 50%; 25% expected). None of the 74 blanks in these experiments was contaminated. We conclude that our delta F508 single-cell assay is efficient and accurate and can be used for analysis of blastomere DNA to diagnose cystic fibrosis before embryo implantation.

Alleles↗
PubMed1992

Molecular cytogenetic analysis of XX males using Y-specific DNA sequences, including SRY.

XX maleness is the most common condition in which testes develop in the absence of a cytogenetically detectable Y chromosome. Using molecular techniques, it is possible to detect Yp sequences in the majority of XX males. In this study, we could detect Y-specific sequences, including the sex-determining region of the Y chromosome (SRY), using fluorescence in situ hybridization. In 5 out of 6 previously unpublished XX males, SRY was translocated onto the terminal part of an X chromosome. This is the first report in which translocation of an SRY-bearing fragment to an X chromosome in XX males could be directly demonstrated.

Adolescent↗