Biomedical subjects

J P Geraedts

Publications and source records attributed to J P Geraedts.

At least 19 recordsLinked to original sources

PubMed2004

ESHRE PGD Consortium 'Best practice guidelines for clinical preimplantation genetic diagnosis (PGD) and preimplantation genetic screening (PGS)'.

Among the many educational materials produced by the European Society of Human Reproduction and Embryology (ESHRE) are guidelines. ESHRE guidelines may be developed for many reasons but their intent is always to promote best quality practices in reproductive medicine. In an era in which preimplantation genetic diagnosis (PGD) has become a reality, we must strive to maintain its efficacy and credibility by offering the safest and most effective treatment available. The dominant motivators for the development of current comprehensive guidelines for best PGD practice were (i) the absence of guidelines and/or regulation for PGD in many countries and (ii) the observation that no consensus exists on many of the clinical and technical aspects of PGD. As a consequence, the ESHRE PGD Consortium undertook to draw up guidelines aimed at giving information, support and guidance to potential, fledgling and established PGD centres. The success of a PGD treatment cycle is the result of great attention to detail. We have strived to provide a similar level of detail in this document and hope that it will assist staff in achieving the best clinical outcome for their patients.

Biopsy↗

PubMed2001

Preimplantation genetic diagnosis (PGD), a collaborative activity of clinical genetic departments and IVF centres.

Preimplantation genetic diagnosis (PGD) requires the combined efforts of geneticists and workers in the field of reproductive medicine. This was studied on the basis of a questionnaire, sent to 35 members of the PGD Consortium of the European Society of Human Reproduction and Embryology (ESHRE). A reply was obtained from 20 centres. They represent the majority of activities in the field of PGD in the world. It is obvious that many of the activities (in vitro fertilisation, embryo culture and biopsy) take place in IVF units while others (counselling and diagnosis) are the responsibility of genetic diagnostic centres. The distances between both units vary considerably. In all but one centre sex determination is offered. Aneuploidy screening is offered in 13 out of 20 centres. PGD of translocations and other structural chromosome abnormalities is offered in all but one centre. The number of monogenic diseases offered varies considerably. In comparison to prenatal diagnosis PGD is more expensive. The majority of these costs are due to the IVF or ICSI procedure. The charges for PGD vary between about 600 euro and 4000 euro. In 16 out of 20 centres the parents to be must sign an informed consent form.

Aneuploidy↗

PubMed2001

Embryo development and chromosomal anomalies after ICSI: effect of the injection procedure.

Intracytoplasmic sperm injection (ICSI) is a delicate procedure requiring considerable skills of the person performing it. Theoretically, the injection procedure could damage cytoplasmic structures in the oocyte, resulting in sublethal cellular injury and/or numerical chromosomal abnormalities that could lead to impaired embryonic development. In the present study, features of the injection procedure were evaluated in a total of 2924 oocytes from 305 cycles. Development to the blastocyst stage was found to be compromised in a group of surplus embryos originating from oocytes in which >6 pl of cytoplasm was aspirated into the injection pipette during the ICSI procedure. Characteristics of the injection procedure as well as blastocyst development of surplus embryos was shown to be significantly different between the four technicians performing the ICSI. Neither the volume of cytoplasm aspirated during the injection procedure, nor the position of the polar body (6 o'clock or 12 o'clock) influenced the mean incidence of disomic cells per blastocyst as revealed by fluorescence in-situ hybridization using probes specific for chromosomes X, Y and 18. In conclusion, certain technical aspects of the injection procedure can affect subsequent embryonic development to the blastocyst stage, but do not seem to influence the rate of chromosomal abnormalities that occur in human pre-implantation embryos.

Blastocyst↗

PubMed2001

[Cloning: applications in humans 1. Technical aspects].

The successful cloning experiments in mammals such as the sheep and mouse prompted speculations on clinical application in humans. Cloning is possible by nucleus transplantation and by embryo splitting. Nucleus transplantation does not result in a genetically completely identical individual because the mitochondrial DNA originates from the ovum donor. Embryo splitting may be regarded as the artificial production of a monozygotic multiplet. Possible applications of cloning in humans belong in the context of reproduction (treatment of couples with subfertility, with genetic problems or with a 'replica motive'), transplantation of genetically identical tissue, and scientific research.

Animals↗

PubMed2001

[Cloning: applications in humans 2. Ethical considerations].

Reproductive cloning in adults/children evokes unfavourable reactions. Direct objections are that cloning is unnatural, that it affects human dignity and violates the individual's right to genetic uniqueness. Consequential objections concern unjustified health risks for the progeny, unjustified psychosocial risks for the clone child and the risk of cloning for eugenetic purposes. There is consensus that reproductive cloning of existing persons is unjustify as yet because of the health risks for the offspring. Reproductive cloning of embryos is possible by means of nucleus transplantation and of embryo splitting. The ethical analysis of reproductive cloning of embryos depends on the purposes and applications. At least some of the moral objections against cloning of adults/children are not or not completely applicable to reproductive cloning of embryos. Conditions to be put to reproductive cloning of embryos are efficacy, safety and, at least for the time being, avoidance of asynchrony in transferring identical embryos. The ethical aspects of its application in the context of genetical reproductive techniques must be evaluated separately. Therapeutic cloning may be acceptable if alternatives are lacking.

Cloning, Organism↗

PubMed2000

[Cloning: applications in humans. I. Technical aspects].

Cloning, Organism↗

PubMed2000

[Cloning: applications in humans. II. Ethical considerations].

Reproductive cloning in adults/children evokes unfavourable reactions. Direct objections are that cloning is unnatural, that it affects human dignity and violates the individual's right to genetic uniqueness. Consequential objections concern unjustified health risks for the progeny, unjustified psychosocial risks for the clone child and the risk of cloning for eugenetic purposes. There is consensus that reproductive cloning of existing persons is unjustifiable as yet because of the health risks for the offspring. Reproductive cloning of embryos is possible by means of nucleus transplantation and of embryo splitting. The ethical analysis of reproductive cloning of embryos depends on the purposes and applications. At least some of the moral objections against cloning of adults/children are not or not completely applicable to reproductive cloning of embryos. Conditions to be put to reproductive cloning of embryos are efficacy, safety and, at least for the time being, avoidance of asynchrony in transferring identical embryos. The ethical aspects of its application in the context of genetical reproductive techniques must be evaluated separately. Therapeutic cloning may be acceptable if alternatives are lacking.

Cloning, Organism↗

PubMed2000

FISH analysis of six chromosomes in unfertilized human oocytes after polar body removal.

PURPOSE: To develop an improved technique for estimating chromosomal abnormalities in human oocytes by fluorescence in situ hybridization (FISH) and to correlate the position of single chromatids with the chromosomal status of the oocytes. METHODS: Oocytes that were at metaphase II about 17-20 hr after insemination or intracytoplasmic sperm injection (ICSI) were treated with pronase to remove the zona pellucida and polar body (PB) and then spread on slides using HCl and Tween 20. Two rounds of FISH were performed using direct-labeled probes: chromosomes 1, 13, 21 (round 1); chromosomes X, 7, 18 (round 2). RESULTS: Of the 63 oocytes from 18 patients (mean age, 32 years), 48 (76%) had one DNA complement as expected, 9 (14%) had 2 DNA complements, 3 (5%) gave incomplete FISH signals, and 3 (5%) were not analyzable. Of the 48 oocytes with one set of DNA, 48% were haploid, 44% were aneuploid for one or more chromosomes, and 8% were polyploid. We also found an increased frequency of predivision of chromatid bivalents in aneuploid oocytes, especially for chromosome 21. CONCLUSIONS: This technique enables simultaneous assessment of six chromosomes in human oocytes, and therefore can be useful for accurately determining the incidence and causes of genetic imbalances in human oocytes and apparently low fertilization rates.

Adult↗

PubMed2000

Comparison of in-vitro development of embryos originating from either conventional in-vitro fertilization or intracytoplasmic sperm injection.

In this retrospective study on 1628 consecutive cycles performed during a period of 4 years, development in vitro is compared of embryos obtained after either conventional in-vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI). At 39-42 h after insemination or injection, embryos obtained after ICSI were significantly (P < 0.01) further developed (mean cell number 3.48 +/- 0.03) as compared with those obtained after IVF (3.22 +/- 0.03), whereas after 63-66 h of in-vitro development this difference was no longer present (mean cell number 6.11 +/- 0.15 versus 6.09 +/- 0.13 respectively). Culture of surplus embryos obtained after IVF resulted in a significantly higher (P < 0.001) mean incidence of blastocyst formation per cycle as compared with the ICSI group (31.8 +/- 1.9 versus 23.0 +/- 1.4 respectively). Blastocysts from both groups consisted of comparable numbers of cells. Blastocyst formation was also significantly higher when embryos were cultured in groups (31.2 +/- 1.8) compared to single culture (23.1 +/- 1.5; P < 0.01), in human tubal fluid (HTF) medium (29.2 +/- 1.7) compared with IVF-50(TM) medium (24.2 +/- 1.6; P < 0.01), and when they were cultured under 5% O(2) (30.3 +/- 1.5) compared with 20% O(2) (21.7 +/- 1.7; P < 0.01). In all culture conditions used, the mean incidence of blastocyst formation per cycle showed comparable differences in favour of the IVF group as compared with the ICSI group.

Adult↗

PubMed2000

Preimplantation genetic diagnosis of a reciprocal translocation t(3;11)(q27.3;q24.3) in siblings.

Preimplantation genetic diagnosis (PGD) was performed in two couples to avoid chromosomally unbalanced progeny in a family in which a brother and a sister carry an identical maternally inherited balanced translocation t(3;11)(q27.3;q24.3). Embryos were biopsied 3 days after fertilization and blastomeres were analysed by fluorescent in-situ hybridization (FISH). Embryos were classified as unbalanced or normal/balanced. In the first case, the male carrier and his wife underwent one IVF/PGD treatment cycle. In all, 18 embryos were analysed. Of those, 15 revealed an unbalanced karyotype. For one embryo, results were not conclusive, from one embryo results were contradictory and one embryo was classified as normal/balanced and subsequently transferred. A singleton pregnancy was achieved. The PGD analysis was confirmed at 16 weeks gestation by amniocentesis. At term, a healthy girl with a balanced karyotype was born. Pregnancy and delivery were without complications. In the second case, the female carrier and her husband underwent two IVF/PGD treatment cycles. During the first cycle, three embryos were analysed. One embryo revealed an unbalanced karyotype and two embryos were designated a normal/balanced karyotype and transferred but no pregnancy was achieved. During the second PGD cycle three embryos were analysed. Of those, none appeared suitable for transfer. The couple decided not to undergo further treatment. Our results indicate that for individuals carrying a reciprocal translocation PGD is a feasible approach to obtain embryos with a normal chromosome balance and to avoid both spontaneous and induced abortion.

Abortion, Spontaneous↗

PubMed2000

Multiplex PCR of polymorphic markers flanking the CFTR gene; a general approach for preimplantation genetic diagnosis of cystic fibrosis.

Cystic fibrosis (CF) is the first monogenic disorder for which single cell preimplantation genetic diagnosis (PGD) has been successfully applied. The spectrum of mutations in CF is extremely heterogeneous, and hence, the development of mutation-specific PGD protocols is impracticable. The current study reports the development and evaluation of a general multiplex marker polymerase chain reaction (PCR) protocol for PGD of CF. Four closely linked highly polymorphic (CA)(n) repeat markers D7S523, D7S486, D7S480 and D7S490, flanking the cystic fibrosis transmembrane regulator (CFTR) gene, were used. In 99% of the single cells tested (100 leukocytes and 50 blastomeres), multiplex PCR results were obtained and the overall allelic drop out (ADO) rate varied from 2 to 5%. After validation for the presence of ADO and additional alleles, 95% of the multiplex PCR results were accepted to construct the marker genotypes. Depending on the genotype of the couple, and taking into account the embryos lost for transfer due to validation criteria (5%), ADO (0-2%) and single recombination (1.1-3%), in general >90% of the embryos could be reliably genotyped by PGD using a single blastomere. The risk of misdiagnosis equals the chance of a double recombination between informative flanking markers and is <0.05%. Therefore, this polymorphic and multi-allelic marker system is a reliable and generally applicable alternative for mutation-directed PGD protocols. Furthermore, it provides a test for the origin of the detected genotype and also gives an indication of the chromosomal ploidy status of the blastomere tested.

Blastomeres↗

PubMed1999

Novel KCNQ1 and HERG missense mutations in Dutch long-QT families.

Congenital long QT syndrome (cLQTS) is electrocardiographically characterized by a prolonged QT interval and polymorphic ventricular arrhythmias (torsade de pointes). These cardiac arrhythmias may result in recurrent syncopes, seizure, or sudden death. LQTS can occur either as an autosomal dominant (Romano Ward) or as an autosomal recessive disorder (Jervell and Lange-Nielsen syndrome). Mutations in at least five genes have been associated with the LQTS. Four genes, encoding cardiac ion channels, have been identified. The most common forms of LQTS are due to mutations in the potassium-channel genes KCNQ1 and HERG. We have screened 24 Dutch LQTS families for mutations in KCNQ1 and HERG. Fourteen missense mutations were identified. Eight of these missense mutations were novel: three in KCNQ1 and five in HERG. Novel missense mutations in KCNQ1 were Y184S, S373P, and W392R and novel missense mutations in HERG were A558P, R582C, G604S, T613M, and F640L. The KCNQ1 mutation G189R and the HERG mutation R582C were detected in two families. The pathogenicity of the mutations was based on segregation in families, absence in control individuals, the nature of the amino acid substitution, and localization in the protein. Genotype-phenotype studies indicated that auditory stimuli as trigger of cardiac events differentiate LQTS2 and LQTS1. In LQTS1, exercise was the predominant trigger. In addition, a number of asymptomatic gene defect carriers were identified. Asymptomatic carriers are still at risk of the development of life-threatening arrhythmias, underlining the importance of DNA analyses for unequivocal diagnosis of patients with LQTS.

Cation Transport Proteins↗

PubMed1999

Effect of oxygen concentration on human in-vitro fertilization and embryo culture.

In this prospective randomized study on 1380 consecutive in-vitro fertilization (IVF) treatments, the results were compared of culture of human oocytes and embryos for the first 2 or 3 days of development in microdroplets of medium under oil using a gas phase containing either atmospheric (approximately 20%) or reduced (5%) O2 concentrations. No significant differences were found between the two groups cultured under either 5% or 20% O2 in rates of fertilization (60 versus 61%, respectively), embryo development at day 2 or 3, pregnancy (26.6 versus 25.4%, respectively), and implantation (13.4 versus 14.0%, respectively). Culture of surplus embryos under 5% O2 resulted in a significantly higher mean incidence of blastocyst formation per cycle as compared to the 20% O2 group (25.8 +/- 2.0 versus 20.4 +/- 1.9, respectively). The mean number of cells of embryos classified as blastocysts by microscopic observation of a blastocoel was significantly higher in the 5% O2 group as compared to the 20% O2 group, both in blastocysts fixed on day 5 (39.8 +/- 1.7 versus 31.9 +/- 1.9, respectively), as well as those fixed on day 6 (45.6 +/- 2.6 versus 33.7 +/- 3.4, respectively). This difference was due to the fact that significantly more blastocysts of the 20% O2 group had an abnormal low cell number of < 25 as compared to the 5% O2 group, both in blastocysts fixed on day 5 (39 versus 22%, respectively), as well as those fixed on day 6 (43 versus 22%, respectively). To conclude, although culture under 5% O2 leads to slightly improved preimplantation embryonic viability, this effect is either too marginal to result in higher pregnancy rates, or low O2 concentrations exert an effect during the later stages of preimplantation development only.

Adult↗

PubMed1999

Perspectives of new reproductive and diagnostic techniques among biologists and physicians, social scientists and ethicists.

The introduction and acceptance of new techniques in the field of reproductive medicine and antenatal genetic diagnosis is a complicated process in which biomedical professionals, and also social scientists and ethicists, play an important role. In this study the attitudes, expectancies and opinions of a panel of biological and medical professionals working in the field of this new technology are compared with those of a panel of concerned social scientists, psychologists, ethicists and leading members of patient groups. Various aspects of the new techniques are investigated: the present and future feasibility, the potential importance, the ethical evaluation and the social acceptance. The social-ethical panel appears to be much more reluctant regarding the importance, ethical values and social acceptability of new techniques than the biomedical panel, in particular, for preimplantation genetic diagnosis and fetal cell sorting large differences exist.

Attitude of Health Personnel↗

PubMed1999

Duplication within chromosome region 15q11-q13 in a patient with similarities to Prader-Willi syndrome confirmed by region-specific and band-specific fish.

We report on a patient presenting with mental retardation and obesity and a proximal duplication of chromosome 15. The patient shared some clinical signs with Prader-Willi syndrome. With a region-specific paint, generated by microdissection, a duplication in region 15q11.2-q13 was shown to be present. Subsequently, FISH with probes localized to chromosome region 15q11.2-q12 and microsatellite analysis was used to characterize this chromosome aberration further and an insertion duplication within the region frequently deleted in Prader-Willi and Angelman syndrome was demonstrated.

Child↗

PubMed1998

[Genetic diagnosis of IVF embryos: preliminary results from 'preimplantation genetic diagnoses' in the Netherlands].

Preimplantation genetic diagnosis (PGD) is a very early form of genetic testing. It involves testing one or two cells taken from a recent embryo of eight cells produced by in vitro fertilization, and selective transfer of genetically normal embryos. So far in the Academic Hospital Maastricht, the Netherlands, 20 couples have undergone PGD, resulting in 6 ongoing pregnancies (one twin pregnancy). In three women the indications for PGD were: cystic fibrosis, sex-linked Pelizaeus-Merzbacher disease and chromosomal translocation, respectively. In the Netherlands PGD is only allowed if there is a high risk of a serious genetic disease. PGD can be carried out in Maastricht for: cystic fibrosis, sex-linked diseases, chromosomal abnormalities, fragile X syndrome, spinal muscular atrophy and myotonic dystrophy. The advantage of PGD is that it excludes the necessity of a therapeutic abortion. Disadvantages ages are the requirement of in vitro fertilization, which has only a 15-20% pregnancy rate, and the experimental nature of the PGD procedure. To date, about 200 children have been born worldwide following PGD.

Adult↗

PubMed1998

[The relationship between genetic polymorphisms and disease, illustrated by the renin-angiotensin-aldosterone system and cardiovascular disease].

The role of molecular genetics in the pathophysiology of various diseases is becoming clearer and clearer. In the field of cardiovascular diseases, molecular genetic aspects have been shown to play a definite role in the aetiology of these diseases. Several molecular-genetic variations called polymorphisms, occur in the population. The genes encoding the different components of the reninangiotensin-aldosterone system (RAAS), an important system in the regulation of the function and structure of the heart and vascular wall, also display polymorphisms. For some of these polymorphisms associations with various cardiovascular and renal diseases have been described. At present, this is particularly clear for the relation between angiotensin-converting-enzyme (ACE) polymorphism and the incidence of atherosclerotic complications and diabetic nephropathy, and for the relation between so-called M235 T-variant of the angiotensinogen gene and hypertension. Future research will have to show where it is worthwhile to use these and other polymorphisms as a marker for genetic risk. In what way the different RAAS-polymorphisms relate to functional abnormalities is as yet unclear, as are the potential therapeutic implications.

Angiotensin II↗

PubMed1998

Characterization of a de novo unbalanced translocation t(14q18q) using microdissection and fluorescence in situ hybridization.

We report on a patient with a de novo translocation between the long arms of chromosomes 14 and 18. The translocation was studied using microdissection in combination with fluorescence in situ hybridization (micro-FISH). Five copies of the chromosomes involved in the translocation were isolated by microdissection and amplified by means of degenerate oligonucleotide primed-polymerase chain reaction (DOP-PCR). Reverse chromosome painting with the biotin-labeled PCR product showed that part of the q-arm of chromosome 18 had no signal. The deletion was characterized further by FISH with band-specific probes and it was concluded that the rearrangement was unbalanced: 46,XY,t(14;18)(14pter-->14q22::18q21.1-->18qter) (18pter-->18q12.2::14q22-->14qter). The patient, who presented with psychomotor retardation, mild obesity, pes equinovarus, strabismus, and facial anomalies, is compared with previously reported patients with an interstitial deletion of band 18q12.

Child, Preschool↗