PGD in 47,XXY Klinefelter's syndrome patients

The use of ICSI has been a major breakthrough in the treatment of male infertility. Even azoospermic patients with focal spermatogenesis in the testis, may benefit from the ICSI technique in order to father a child. As ICSI use has become more common, centres have introduced infertility treatment for Klinefelter patients. To date, 34 healthy children have been born using ICSI without PGD, and the conception of one 47,XXY fetus has been reported. In view of the possible risk of an increased gonosome number in the spermatozoa of Klinefelter patients, a safer approach--offering these couples ICSI combined with PGD--has been used, and has resulted in the birth of three healthy children. Couples in which the male suffered from Klinefelter's syndrome were first treated in 1995; these patients were offered ICSI + PGD using FISH technology, notably to enumerate the X and Y chromosomes. ICSI + PGD was performed in 32 cycles of 20 couples with spermatozoa originating from a fresh ejaculate (n = 1), testicular biopsy (n = 21) or frozen-thawed testicular biopsy (n = 10). Normal fertilization occurred in 56.0 +/- 22.4% of the successfully injected oocytes. On day 3 of development, 119 embryos from 29 cycles were of sufficient quality to undergo biopsy and subsequent PGD; a positive result was obtained in 113 embryos. Embryos were available for transfer in 26 cycles, with a mean of 1.6 +/- 0.6 embryos per transfer. Eight pregnancies were obtained, and five resulted in a delivery. A total of 113 embryos from couples with Klinefelter's syndrome was compared with 578 embryos from control couples with X-linked disease where PGD was used to determine gender. A significant fall occurred in the rate of normal embryos for couples with Klinefelter's syndrome (54.0%) compared with controls (77.2%). Moreover, a significantly increased risk of abnormalities was observed for sex chromosomes and autosomes; for each autosome separately, this reached significance level for chromosomes 18 and 21 only. Hence, a cautious approach is warranted in advising couples with non-mosaic Klinefelter's syndrome. Moreover, the use of ICSI + PGD or prenatal diagnosis should be carefully considered.     

Successful preimplantation genetic diagnosis is related to the number of available cumulus-oocyte complexes

The inheritance pattern of monogenic inheritable disorders influences the proportion of unaffected embryos after preimplantation genetic diagnosis (PGD). We aimed to investigate the influence of the number of cumulus-oocyte complexes (COC) on the outcome after PGD. Eighty-four cycles of 47 couples were included in our analysis. All couples were at risk of transmitting autosomal recessive, autosomal dominant, X-linked single gene disorders or sexaneuploidies to their offspring. One PGD cycle was carried out for a Yq-deletion of the man. The correlation between the numbers of COC and biopsied embryos and between the numbers of COC and unaffected embryos was highly significant (P <0.05). A pregnancy occurred in 15 cycles and a minimum of six COC were needed to achieve a pregnancy. Thirteen pregnancies were observed in cycles with at least 9 COC. The transfer rate and number of transferred embryos per cycle in the subgroups with <9 COC and > or =9 COC were significantly higher in the latter. Although pregnancy rates did not differ significantly between the two subgroups (probably due to the low number of pregnancies), our data indicate that it is justifiable to cancel PGD cycles in which it is expected that <6 COC will be retrieved and that the couple should be informed about the poor prognosis if <9 COC are retrieved.      

Strategies and clinical outcome of 250 cycles of Preimplantation Genetic Diagnosis for single gene disorders

BACKGROUND: We report on our experience with preimplantation genetic diagnosis (PGD) for single gene disorders (SGDs), from 1999 to 2004, describing strategies and overall clinical outcome of 250 cycles in 174 couples for 23 different genetic conditions. METHODS: PGD cycles included 15 for autosomal dominant, 148 for autosomal recessive and 19 for X-linked SGDs. In addition, 68 cycles of PGD for SGDs were performed in combination with HLA matching. The strategy in each case used an initial multiplex PCR, followed by minisequencing to identify the mutation(s) combined with multiplex PCR for closely linked informative markers to increase accuracy. Linkage analysis, using intragenic and/or extragenic polymorphic microsatellite markers, was performed in cases where the disease-causing mutation(s) was unknown or undetectable. RESULTS: In 250 PGD cycles, a total of 1961 cleavage stage embryos were biopsied. PCR was successful in 3409 out of 3149 (92.4%) biopsied blastomeres and a diagnosis was possible in 1849 (94.3%) embryos. Four hundred and twenty-seven embryos were transferred in 211 cycles, resulting in 71 pregnancies (33.6% per embryo transfer), including 15 biochemical pregnancies, six spontaneous miscarriages, two ectopic pregnancies, which were terminated, and nine pregnancies which are still ongoing. The remaining pregnancies were confirmed to be unaffected and went to term without complications, resulting in the birth of 35 healthy babies. CONCLUSIONS: Minisequencing for mutation detection combined with multiplex fluorescence PCR for linkage analysis is an efficient, accurate and widely applicable strategy for PGD of SGDs. Our experience provides a further demonstration that PGD is an effective clinical tool and a useful option for many couples with a high risk of transmitting a genetic disease.     

Improving clinical preimplantation genetic diagnosis for cystic fibrosis by duplex PCR using two polymorphic markers or one polymorphic marker in combination with the detection of the DeltaF508 mutation

Cystic fibrosis (CF) is an autosomal recessive disease characterized by obstruction and chronic infection of the respiratory tract and pancreatic insufficiency. The first preimplantation genetic diagnosis (PGD) for CF was carried out in 1992. At our centre the first cycle was performed in 1993. However, the number of known CF mutations is >1000, so developing mutation-specific PCR protocols for PGD is unfeasible. This is why a number of marker-based duplex PCRs were developed at the single cell level. A duplex PCR of a mutation and one or two microsatellites is not only a diagnostic tool, but it can also be used as a control for allele drop-out and contamination. During PGD, embryos obtained in vitro are analysed for the presence or absence of a particular genetic disease, after which only embryos shown to be free of this disease are returned to the mother. In total, 22 PGD cycles with duplex PCR (IVS8CA/IVS17BTA, DeltaF508/IVS8CA, DeltaF508/IVS17BTA and D7S486/D7S490) were carried out in 16 couples, which resulted in four ongoing pregnancies and one miscarriage.     

An evaluation of PGD in clinical genetic services through 3 years application for prevention of beta-thalassaemia major and sickle cell thalassaemia

PGD represents an alternative within prenatal diagnosis services, which avoids terminating affected on-going pregnancies. In Greece, prevention programmes for haemoglobinopathies, including the option of prenatal diagnosis, are well established. Following optimization of a single-cell genotyping strategy (designed to be applicable for the majority of beta-thalassaemia major or sickle thalassaemia genotype interactions) along with close collaboration with an IVF unit, we integrated the option of PGD for at-risk couples with a problematic reproductive history. A total of 59 couples requesting PGD were counselled, of whom 41 initiated 63 PGD cycles. Following standard assisted reproduction treatment for oocyte retrieval, 20 cycles were cancelled (too few oocytes and/or poor quality embryos), but in 43 cycles single blastomeres were biopsied from 3 day embryos and genotyped (total 302). Diagnosis was achieved for 236 embryos, and 100 of 125 unaffected embryos were transferred. Sixteen pregnancies were established, although six were lost within the first trimester. Ten pregnancies underwent second trimester prenatal diagnosis, with nine pregnancies (13 babies: six singletons, two twins and one triplet) confirmed unaffected, although one singleton was a PGD misdiagnosis and terminated. The triplet pregnancy was selectively reduced to twins, and nine pregnancies went to term, with 12 healthy babies born. This report highlights advantages, limitations and approaches towards improvement when incorporating PGD within genetic services for a common recessive disease.     

Prognostic role of preimplantation genetic diagnosis for aneuploidy in assisted reproductive technology outcome

BACKGROUND: Preimplantation genetic diagnosis (PGD) for aneuploidy is recommended to couples at risk of generating chromosomally abnormal embryos. The aim of this study was to demonstrate that PGD for aneuploidy has an important role in the prognosis of subsequent treatments. METHODS: A total of 389 couples underwent their first PGD for aneuploidy due to either female age >or=38 years (n = 266) or >or=3 previous unsuccessful cycles (n = 123). After the first PGD followed by an unsuccessful treatment cycle, 141 couples underwent 175 subsequent PGD cycles. These patients were divided into three groups depending on the number of euploid embryos available for transfer in their first PGD cycle: group A included patients where no euploid embryos were diagnosed; group B included patients who had only one euploid embryo; and group C included patients with at least two normal embryos resulting from chromosomal analysis. RESULTS: In subsequent cycles, group A patients underwent significantly fewer transfers (45%) compared with group B (69%, P < 0.05) and group C patients (85%, P < 0.001). The pregnancy rate per transfer was significantly decreased in group A (15%) compared with group B (36%; P < 0.02) and group C (30%; P < 0.03). Accordingly, the live birth rate per patient was significantly lower in group A compared with group C (8.5% versus 30%; P < 0.005). CONCLUSIONS: The outcome of the first PGD for aneuploidy may have a predictive role for subsequent attempts.     

Preimplantation genetic diagnosis for neurofibromatosis type 1

PGD is an alternative to prenatal diagnosis that circumvents therapeutic abortion. Diagnosis is carried out on single cells obtained from three-day-old embryos, and only those that are free of the disease under consideration are transferred to the mother. Neurofibromatosis type 1 (NF1) is a common neurocutaneous disorder, inherited as an autosomal dominant trait and caused by mutations in the NF1 gene. For some patients, PGD may be the only acceptable manner to ensure the birth of unaffected children. Because of the large number of known NF1 mutations, the development of mutation-specific single-cell protocols is impractical, labour-intensive and expensive. This paper discusses the development of five PGD protocols, three of which are based on multiplex PCR for microsatellite-markers linked to the NF1 gene. After a linkage study, the diagnosis can be established through the markers, thereby obviating the need to detect the mutation itself. This not only ensures the accurate diagnosis of the embryos, but also a prompt acceptance of PGD referrals since one protocol can be useful for several couples. In addition, two mutation-specific PCRs were developed for two couples where a marker-based protocol was not applicable. In total, 16 PGD cycles were carried out for six couples, which resulted in one ongoing pregnancy and the delivery of a healthy unaffected boy.     

Successful application of preimplantation genetic diagnosis for beta-thalassaemia and sickle cell anaemia in Italy

BACKGROUND: In Italy, the autosomal recessive diseases beta-thalassaemia and sickle cell anaemia are so widespread that in some regions they can be defined as 'social diseases'. In this study, nine clinical applications of preimplantation genetic diagnosis (PGD) were performed for beta-thalassaemia and sickle cell anaemia on seven Sicilian couples and carriers of beta-globin gene mutations. METHODS AND RESULTS: The studied mutations were: Cd39, HbS, IVS1 nt1, IVS1 nt6 and IVS1 nt110. ICSI was performed with partner's sperm on 131 out of 147 retrieved oocytes, and this resulted in 72 zygotes; 32 embryos were successfully biopsied on day 3. The biopsied blastomeres were lysed and the beta-globin alleles amplified by nested PCR. The mutation diagnosis was performed by restriction enzyme digestion and reverse dot-blot. The amplification efficacy was 97.2%. The genotype study of non-transferred and surplus embryos showed that the allele drop-out rate was 8.6%. Seventeen embryos were transferred in utero on day 4. All couples received an embryo transfer; of the four pregnancies obtained, three resulted in live births and one miscarried at 11 weeks. Prenatal diagnosis at the 11th week and miscarriage material analysis confirmed the PGD results. CONCLUSIONS: These studies represent the first successful application of PGD for beta-thalassaemia and sickle cell anaemia in Italy.     

Intracytoplasmic sperm injection (ICSI) in 2006: evidence and evolution

The introduction of intracytoplasmic sperm injection (ICSI)in 1992 has dramatically changed the management of severe maleinfertility. In severe male infertility, live birth rates withICSI are superior to those with other non-donor treatments.In non-male infertility, however, pregnancy rates are not betterwith ICSI than with in vitro fertilization (IVF). With obstructiveor non-obstructive azoospermia, reasonable pregnancy rates arenow possible with ICSI after recovery of sperm from the testesfollowed by ICSI. Genetic counselling is indicated for severemale infertility, whether or not ICSI is considered. ICSI isindicated in preimplantation genetic diagnosis (PGD) to avoidcontamination by extraneous DNA in the case of PCR-based testingand to increase the number of embryos available for testing.In turn, PGD may be indicated in pregnancies that are at highrisk of aneuploidy because of genetic factors associated withazoospermia. As with IVF, not all couples succeed, but 2% ofcouples with failed ICSI cycles will conceive without treatment.ICSI outcome studies indicate that there is a significant increasein prematurity, low birthweight, and perinatal mortality associatedwith single and multiple births, similar to the outcomes ofconventional IVF. However, as evidenced in long-term follow-upstudies, the higher rates of urogenital abnormalities and increaseduse of healthcare may be associated with paternal characteristics.     

A Danish national cohort of 730 infants born after intracytoplasmic sperm injection (ICSI) 1994-1997.

This national cohort study included all clinical pregnancies obtained after intracytoplasmic sperm injection (ICSI) registered in Denmark between January 1994 and July 1997 at five public and eight private fertility clinics. Laboratory and clinical data were obtained from the fertility clinics. The couples answered a questionnaire regarding the pregnancy and the health of the child (response rate 94%). Data validation was carried out through discharge charts. The mean age of the women was 32.1 years. In 84.2% of couples, male factor was the main reason for performing ICSI, and in 4.8% epididymal spermatozoa were used. The mean number of embryos replaced was 2.3 (range 1-3) and in 95% of cases fresh embryos were transferred. Only 183 women (28.5%) underwent prenatal diagnosis, resulting in 209 karyotypes with seven (3.3%) chromosome aberrations. Six major chromosomal abnormalities (2.9%) and one inherited structural chromosome aberration (0.5%) were found, but no sex chromosome aberrations. The frequency of multiple birth, Caesarean section rate, gestational age, preterm birth, and birth weight were comparable with previous studies. The perinatal mortality rate was 13.7 per 1000 children born with a gestational age of 24 weeks or more. In 2.2% (n = 16) of the liveborn infants, and in 2.7% (n = 20) of all infants, major birth defects were reported by the parents. Minor birth defects were found in nine liveborn infants (1.2%). In conclusion, the results of this study on outcome of ICSI pregnancies are in line with earlier reports, except that no sex chromosome abnormalities were found.     

Preimplantation genetic diagnosis for Charcot-Marie-Tooth disease type 1A

Charcot-Marie-Tooth (CMT) disease is the 'common' name for a range of hereditary peripheral neuropathies. CMT1 is the most common form and is transmitted in an autosomal dominant manner. CMT1A maps to chromosome 17p11.2 and is caused, in the majority of cases, by a 1.5 Mb DNA duplication, that includes the peripheral myelin protein 22 (PMP) gene. This paper reports on preimplantation genetic diagnosis (PGD) for CMT1A in five couples. The CMT1A duplication was detected by fluorescent PCR analysis using polymorphic (CA)n markers localized within the duplication. Single-cell PCR on blastomeres allowed genetic analysis of embryos obtained after ICSI. Only healthy unaffected embryos were transferred to the uterus. PCR experiments with single EBV-transformed lymphoblasts or with research blastomeres allowed the evaluation of amplification efficiencies, as well as contamination and allele drop-out (ADO) rates for each PCR protocol. Three simplex PCR protocols (using one primer pair) and two duplex PCR protocols (using two primer pairs) were developed for CMT1A. Additionally, a protocol using all three primer pairs in triplex was also established. Thirteen clinical ICSI-PGD cycles were performed for five couples (12 simplex PCR cycles and one duplex PCR cycle), resulting in seven embryo transfers. Three singleton pregnancies ensued in two couples and three healthy babies were delivered. This report describes different fluorescent PCR-based tests which allow efficient and accurate single-cell level detection of the CMT1A duplication. On the basis of the presence of the healthy allele of the affected parent-to-be (and/or absence of the affected one), healthy embryos can be selected for transfer. The assays are suitable for PGD for other couples who present with the same CMT1A duplication [depending on their informativity for the (CA)n markers available] as described here.     

Overall prognosis with current treatment of infertility

Few reports provide pregnancy or birth rates for large groups of infertile couples having a comprehensive range of treatments. This model utilizes published evidence about diagnosis, treatment, the duration of treatment and the proportion of couples receiving treatment. Assisted reproduction technology treatment (ART) utilization was set arbitrarily at three levels: 3, 10 or 50% of the couples that had no live birth after conventional treatment. For each diagnosis and treatment the model estimated total live births, singleton live births and multiple live births per 10,000 couples. The overall live birth rate with non-ART treatment would be 37%, involving 3,725 live births, of which 3,478 (93%) would be singleton and 247 (7%) would be multiple. With ART utilization at 3, 10 and 50% of couples with persistent infertility in each diagnostic category, live birth rates were 39, 43 and 47% respectively, with 8, 10 and 12% multiple births. The corresponding utilization of ART would be 244, 813 and 1481 ART cycles per 10(6) population per annum. Typical management of infertility would fall short of 50% live births even with extensive utilization of ART. Underlying unknown untreatable factors remain barriers to greater overall success in the treatment of infertility.     

Current concepts in preimplantation genetic diagnosis (PGD): a molecular biologist's view

The first clinically applied preimplantation genetic diagnosis (PGD) was reported more than a decade ago and since then PGD has known an exponential growth. This first report described the use of PCR to sex embryos from couples at risk for X-linked diseases. Not surprisingly, in the first years, the development of PCR-based tests led to PGD for well-known monogenic diseases such as cystic fibrosis and thalassaemia. When fluorescent in-situ hybridization (FISH) was introduced it quickly replaced PCR-based methods, which had led to misdiagnoses, for sexing of embryos. FISH was also quickly introduced for aneuploidy screening, which has as its main aim the improvement of IVF results in patients with poor reproductive outcome, and later for PGD in translocation carriers. In this review, PGD for patients with a pre-existing genetic risk will be discussed, i.e. the monogenic diseases and the translocations, as well as different biopsy methods and promising new developments.     

Preimplantation genetic diagnosis (PGD) for Huntington's disease: the experience of three European centres

This study provides an overview of 13 years of experience of preimplantation genetic diagnosis (PGD) for Huntington's disease (HD) at three European PGD centres in Brussels, Maastricht and Strasbourg. Information on all 331 PGD intakes for HD, couples' reproductive history, PGD approach, treatment cycles and outcomes between 1995 and 2008 were collected prospectively. Of 331 couples for intake, 68% requested direct testing and 32% exclusion testing (with a preponderance of French couples). At the time of PGD intake, 39% of women had experienced one or more pregnancies. A history of pregnancy termination after prenatal diagnosis was observed more frequently in the direct testing group (25%) than in the exclusion group (10%; P=0.0027). PGD workup was based on two approaches: (1) direct testing of the CAG-triplet repeat and (2) linkage analysis using intragenic or flanking microsatellite markers of the HTT gene. In total, 257 couples had started workup and 174 couples (70% direct testing, 30% exclusion testing) completed at least one PGD cycle. In total, 389 cycles continued to oocyte retrieval (OR). The delivery rates per OR were 19.8%, and per embryo transfer 24.8%, resulting in 77 deliveries and the birth of 90 children. We conclude that PGD is a valuable and safe reproductive option for HD carriers and couples at risk of transmitting HD.     

Use of co-culture of human embryos on Vero cells to improve clinical implantation rate

Co-culture of human embryos (n = 384 cycles) to the blastocyst stage using Vero cell monolayers was carried out between August 1995 and December 1997. A total of 2868 zygotes were co-cultured and 1027 embryos reached the blastocyst stage (blastocyst formation rate 35.8%). The blastocysts were frozen in 43.7% of patients. A mean of 1.8 blastocysts was transferred per patient and 95 pregnancies were obtained (pregnancy rate/cycle 24.7%). The blastocyst implantation rate was 23.6%. Miscarriage occurred in 15 patients (15.7%) and ectopic pregnancy in three (3.1%) patients. The multiple pregnancy rate was 32.6%. No differences were observed in the blastocyst rate between poor, normal or high response patients. Blastocyst formation was significantly lower when frozen donor spermatozoa were used. Significantly higher pregnancy rates per transfer and blastocyst implantation rates were attained when embryos were transferred on days 5 or 6 compared with day 7. No advantage was observed when co-culture was used in first cycle IVF patients, in comparison with conventional day 2 replacements. The use of blastocysts for preimplantation genetic diagnosis (PGD) increases the diagnostic reliability and widens diagnostic possibilities. A total of 215 cycles with frozen-thawed co-cultured blastocysts were carried out, with a pregnancy rate of 22.7% per replacement.     

Seven years of intracytoplasmic sperm injection and follow-up of 1987 subsequent children

Intracytoplasmic sperm injection (ICSI) with ejaculated, epididymal or testicular spermatozoa was first successful in 1992 and has since become the widely accepted treatment for couples with severe male-factor infertility. The outcome of several thousands of ICSI cycles in terms of fertilization, embryo cleavage and implantation is similar to that for conventional in-vitro fertilization in couples with tubal or idiopathic infertility. To evaluate the important issue of safety of the new technique of ICSI, a prospective follow-up study of 1987 children born after ICSI was carried out. The aim was to compile data on karyotypes, congenital malformations, growth parameters and developmental milestones. Parents' agreement to genetic counselling was obtained as well as prenatal diagnosis, followed by a physical examination of the children at 2 months, 1 year and 2 years. Between April 1991 and August 1997, 1699, 91 and 118 children were born after ICSI with ejaculated, epididymal and testicular spermatozoa respectively; 79 children were born from cryopreserved ICSI embryos. In all, 1082 karyotypes were determined by prenatal diagnosis, 18 of which were abnormal and de novo (1.66%) (nine each of autosomal and sex chromosomal aberrations), and 10 karyotypes (0.92%) were inherited structural aberrations. Of these, nine (eight balanced structural aberrations and one unbalanced trisomy 21) were transmitted from the father. Ten pregnancies were terminated after prenatal karyotyping or DNA testing. Forty-six major malformations (2.3%) were observed at birth. Seven malformations, observed by prenatal ultrasound, were terminated. Twenty-one (1.1 %) stillbirths, including four with major malformations, occurred later than 20 weeks of pregnancy. Mean gestational age at birth was 38.7 weeks for singletons, 36.0 weeks for twins and 32.0 weeks for triplets. No specifically higher incidence of malformations was found in any given subgroup.     

Preimplantation genetic diagnosis and chromosome analysis of blastomeres using comparative genomic hybridization

Numerical chromosome errors are known to be common in early human embryos and probably make a significant contribution to early pregnancy loss and implantation failure in IVF patients. Over recent years fluorescent in situ hybridization (FISH) has been used to document embryonic aneuploidies. Many IVF laboratories perform preimplantation genetic diagnosis (PGD) with FISH to select embryos that are free from some aneuploidies in an attempt to improve implantation, pregnancy and live birth rates in particular categories of IVF patients. The usefulness of FISH is limited because only a few chromosomes can be detected simultaneously in a single biopsied cell. Complete karyotyping at the single cell level can now be achieved by comparative genomic hybridization (CGH). CGH enables not only enumeration of all chromosomes but gives a more complete picture of the entire length of each chromosome and has demonstrated that chromosomal breakages and partial aneuploidies exist in embryos. CGH has provided invaluable information about the extent of mosaicism and aneuploidy of all chromosomes in early human conceptuses. CGH has been applied to clinical PGD and has resulted in the birth of healthy babies from embryos whose full karyotype was determined in the preimplantation phase.     

Robertsonian translocations--reproductive risks and indications for preimplantation genetic diagnosis.

BACKGROUND: Robertsonian translocations carry reproductive risks that are dependent on the chromosomes involved and the sex of the carrier. We describe five couples that presented for preimplantation genetic diagnosis (PGD). METHODS: PGD was carried out using cleavage-stage (day 3) embryo biopsy, fluorescence in-situ hybridization (FISH) with locus-specific probes, and day 4 embryo transfer. RESULTS: Couple A (45,XX,der(14;21)(q10;q10)) had two previous pregnancies, one with translocation trisomy 21. A successful singleton pregnancy followed two cycles of PGD. Couple B (45,XX,der(13;14)(q10;q10)) had four miscarriages, two with translocation trisomy 14. One cycle of PGD resulted in triplets. Couple C (45,XX,der(13;14)(q10;q10)) had four years of infertility; two cycles were unsuccessful. Couple D (45,XY,der(13;14)(q10;q10)) presented with oligozoospermia. A singleton pregnancy followed two cycles of PGD. Couple E (45,XY,der(13;14)(q10;q10)) had a sperm count within the normal range and low levels of aneuploid spermatozoa. PGD was therefore not recommended. No evidence for a high incidence of embryos with chaotic or mosaic chromosome complements was found. CONCLUSIONS: For fertile couples, careful risk assessment and genetic counselling should precede consideration for PGD. Where translocation couples need assisted conception for subfertility, PGD is a valuable screen for imbalance, even when the risk of viable chromosome abnormality is low.     

Benefits and drawbacks of preimplantation genetic diagnosis (PGD) for reciprocal translocations: lessons from a prospective cohort study

Preimplantation genetic diagnosis (PGD) using fluorescence in situ hybridisation probes was carried out for 59 couples carrying reciprocal translocations. Before treatment, 85% of pregnancies had resulted in spontaneous miscarriage and five couples had achieved a healthy live-birth delivery. Following treatment, 33% of pregnancies failed and 21of 59 couples had a healthy live-born child. The accuracy of diagnosis was 92% (8% false abnormal and 0% false normal results). The overall incidence of 2:2 alternate segregation products was 44% however, products consistent with 2:2 adjacent segregation were ∼twice as likely from male heterozygotes, and those with 3:1 disjunction were three times more likely from female heterozygotes. Our results indicate that up to three stimulation cycles per couple would give an ∼50% chance of a successful live birth, with the risk of miscarriage reduced to the level found in the general population. In our study, 87% of all normal/balanced embryos available were identified as being suitable for transfer. We conclude that PGD provides benefit for couples with high-risk translocations by reducing the risk of miscarriage and avoiding a pregnancy with an unbalanced form of the translocation; however, for fertile carriers of translocations with a low risk of conceiving a chromosomally unbalanced offspring, natural conception may be a more viable option.     

Healthy births and ongoing pregnancies obtained by preimplantation genetic diagnosis in patients with advanced maternal age and recurrent implantation failure

Preimplantation genetic diagnosis (PGD) and subsequent embryo development was evaluated in 72 couples presenting at our centre for intracytoplasmic sperm injection (ICSI) due to severe male factor. The embryo biopsies were performed in Ca(2+)/Mg(2+)-free medium. These patients were further divided into those with advanced maternal age (AMA, n = 49) and those with recurrent implantation failure (RIF, n = 23). Fluorescence in-situ hybridization (FISH) was carried out on 329 blastomeres (91.3%) with probes for the X, Y, 13, 18 and 21 chromosomes. The chromosomal abnormality rate was 41.3% with no significant difference between the AMA and RIF groups. Aneuploidy accounted for the majority (72.8%) of chromosomal abnormalities. Out of 329 embryos, 84.2% had cleaved after 24 h and 15.1% had arrested. Embryos were transferred in 70 patients and 22 pregnancies were achieved (31.4% with an ongoing pregnancy rate of 28.5%). There were no significant differences between the pregnancy rates of the AMA and RIF groups (32.5 and 30% respectively). Therefore PGD should be offered to patients with AMA and RIF. Furthermore, the use of Ca(2+)/Mg(2+)-free medium during the blastomere biopsy facilitates the procedure, while further embryo cleavage, ongoing pregnancies and healthy births are possible.