Preimplantation genetic diagnosis(PGD) for reciprocal translocations

Normal birth following PGD for reciprocal translocation after serial vitrification of oocytes from a poor responder: a case report

This case study reports the first successful birth outcome following preimplantation genetic diagnosis (PGD) for a chromosome translocation in embryos generated by serial vitrification of oocytes. A couple presented to the fertility clinic with 2 years of primary infertility. The woman was diagnosed with poor ovarian reserve and her partner was diagnosed with severe oligoteratozoospermia and the reciprocal translocation 46,XY,t(1;7)(p36.1;q11.23). Following counselling, the couple opted for serial vitrification of oocytes followed by PGD. A total of 31 oocytes were obtained in five egg collection cycles over a period of 12 months and 27 metaphase-II oocytes were vitrified. Nineteen of the 27 vitrified oocytes survived warming: 14 oocytes from the vitrified group and three oocytes from the fresh cycle were fertilized by intracytoplasmic sperm injection. Eleven embryos, including three from the fresh cycle, were biopsied on day 3 post insemination. Fluorescence in-situ hybridization was performed for the specific chromosomes involved in translocation. Only two embryos from the cryopreservation cycles were diagnosed as normal/balanced, one of which was transferred on day 5 post insemination. A normal healthy female infant was born at week 42 of gestation.

Derivation of the King's College London human embryonic stem cell lines

Since the derivation of the first human embryonic stem cell (hESC) line in 1998, there has been substantial interest in the potential of these cells for regenerative medicine and cell therapy and in the use of hESCs carrying clinically relevant genetic mutations as models for disease research and therapeutic target identification. There is still a need to improve derivation efficiency and further the understanding of the basic biology of these cells and to develop clinical grade culture systems with the aim of producing cell lines suitable for subsequent manipulation for therapy. The derivation of initial hESC lines at King's College London is discussed here, with focus on derivation methodology. Each of the derivations was distinctive. Although the stage and morphology of each blastocyst were generally similar in each attempt, the behaviour of the colonies was unpredictable; colony morphology and development was different with each attempt. Days 5, 6 and 7 blastocysts were used successfully, and the number of days until appearance of stem-like cells varied from 4 to 14 d. Routine characterisation analyses were performed on three lines, all of which displayed appropriate marker expression and survived cryopreservation-thaw cycles. From the lines discussed, four are at various stages of the deposition process with the UKSCB, one is pending submission and two are unsuitable for banking. Continued open and transparent reporting of results and collaborations will maximise the efficiency of derivation and facilitate the development of standardised protocols for the derivation and early culture of hESC lines.

Single-cell DNA and FISH analysis for application to preimplantation genetic diagnosis

Preimplantation genetic testing, which includes preimplantation genetic diagnosis (PGD) and preimplantation genetic screening (PGS), is a form of a very early prenatal testing. The goal of this method is to avoid transfer of embryos affected with a specific genetic disease or condition. This unit describes the steps involved in amplifying DNA from a single blastomere and specific assays for detecting a variety of DNA mutations. For some assays, whole-genome amplification by primer-extension preamplification (PEP) is performed prior to analysis. Support protocols describe the biopsy of one or two blastomeres from the developing preimplantation embryo, isolation for further investigation of all blastomeres from embryos shown to have the mutant allele, and isolation of single lymphocytes or lymphoblastoid cells as models for single-cell DNA analysis. A procedure for FISH analysis on single interphase blastomeres is provided along with support protocols for probe preparation and probe validation, which is recommended as a preliminary step before performing any PGD or PGS FISH analysis.

Blastocyst trophectoderm biopsy and preimplantation genetic diagnosis for familial monogenic disorders and chromosomal translocations

OBJECTIVE

Modern in vitro fertilization practices involve transfer of embryos as blastocysts, when anabolic metabolism is well established and pregnancy rates can be maintained while transferring embryos singly to avoid multiple pregnancies. Embryo biopsy for preimplantation genetic diagnosis (PGD), however, is generally performed on day 3, when the embryo comprises just 6 to 8 cells, one or two of which are removed for testing. Implantation rates and clinical pregnancy rates have remained relatively low and a harmful effect from losing one or more cells from such early embryos has not been excluded.

METHODS

We performed a sequential study involving 399 egg retrievals and 1879 embryo biopsies for patients undergoing PGD to avoid a serious monogenic disease or an unbalanced chromosomal translocation. We compared implantation and viable pregnancy rates after biopsies taken on day 3 (cleavage-stage biopsy) with biopsies delayed until day 5 or 6, when the embryo is a blastocyst and 5 or more cells can be sampled from the trophectoderm while the inner cell mass, from which the fetus develops, remains intact. All embryos were transferred as blastocysts.

RESULTS

Despite fewer blastocysts than cleavage embryos biopsied and tested (3.6 compared to 6.6), implantation rates per embryo transferred were 43.4% if biopsied at the blastocyst stage and 25.6% if biopsied at the cleavage stage (P < 0.01), with ongoing or live-birth pregnancy rates per egg retrieval of 34.2% (average transfer number 1.1) for blastocyst biopsies and 25.5% (transfer number 1.6) for cleavage stage biopsies (P < 0.05, 1-tailed). The multiple pregnancy rate for monogenic disease exclusion fell from 16.7% to 2% (P = 0.04, 1-tailed).

CONCLUSIONS

For exclusion of genetic disease, day 5-6 blastocyst-stage biopsies are more likely to be followed by implantation and singleton births than is the case after PGD performed on day 3.

Underlying karyotype abnormalities in IVF/ICSI patients

Cytogenetic investigations are performed in couples asking for IVF or intracytoplasmic sperm injection (ICSI) treatment. These serve a diagnostic purpose because male or female infertility might have a chromosomal origin. Chromosomal aberrations found in these patients include numerical abnormalities, such as Klinefelter syndrome, XYY karyotype or Turner syndrome and its variants; sex reversions, such as XX males or XY females; and also structural abnormalities, such as Robertsonian or reciprocal translocations and inversions. Finding the chromosomal origin of infertility in a patient also has a prognostic value because it aids the management of pregnancies obtained after IVF or ICSI and may lead to a proposal of prenatal or preimplantation genetic diagnosis.

ESHRE PGD consortium data collection VII: cycles from January to December 2004 with pregnancy follow-up to October 2005

The seventh report of the ESHRE PGD Consortium is presented documenting cycles collected for the calendar year 2004 and follow-up of the pregnancies and babies born subsequent to these cycles up to October 2005. Since the beginning of the data collections, there has been a steady increase in the number of cycles, pregnancies and babies reported. For data collection VII, 45 centres have participated, reporting on 3358 cycles to oocyte retrieval (OR), 679 pregnancies and 528 babies born. Five hundred and fifty nine OR were reported for chromosomal abnormalities, 113 OR for sexing for X-linked diseases, 520 OR for monogenic diseases, 2087 OR for PGS, and 79 OR for social sexing. Data VII is compared with the cumulative data for data collections I-VI.

Pregnancy outcomes of reciprocal translocation carriers who have a history of repeated pregnancy loss

Cytogenetic investigation of 2,324 Japanese couples with repeated pregnancy loss revealed that 4.91% of couples (n = 114) had chromosome abnormalities including reciprocal translocation (n = 74), Robertsonian translocation (n = 23), and inversion (n = 10). Parental reciprocal translocation was a significant predictor of subsequent miscarriage (adjusted odds ratio: 3.6, 95% confidence interval: 1.8-7.1), and most of the miscarriages of the carrier couples were inevitable because of abnormal karyotypes, despite appropriate treatments.

ESHRE PGD Consortium data collection VI: cycles from January to December 2003 with pregnancy follow-up to October 2004

The sixth report of the ESHRE PGD Consortium is presented, relating to cycles collected for the calendar year 2003 and follow-up of the pregnancies and babies born up to October 2004. Since the beginning of the data collections, there has been a steady rise in the number of cycles, pregnancies and babies reported. For this report, 50 centres participated, reporting on 2984 cycles, 501 pregnancies and 373 babies born. Five hundred and twenty-nine cycles were reported for chromosomal abnormalities, 516 cycles were reported for monogenic diseases, 137 cycles were reported for sexing for X-linked diseases, 1722 cycles were reported for preimplantation genetic screening (PGS) and 80 cycles were reported for social sexing. Data VI is compared to the cumulative data for data collections I-V.

Three hundred and thirty cycles of preimplantation genetic diagnosis for serious genetic disease: clinical considerations affecting outcome

OBJECTIVE

To report on our experience with preimplantation genetic diagnosis (PGD) cycles performed for serious genetic disease in relation to the clinical factors affecting outcome.

DESIGN

Retrospective review of data from a single centre.

SETTING

Tertiary referral PGD centre in a London teaching hospital.

METHODS

The PGD cycles included 172 cycles for chromosome rearrangements, 96 cycles for single-gene disorders and 62 cycles for X-linked disorders. In vitro fertilisation was the preferred method in chromosome rearrangement and X-linked cases, while intra cytoplasmic sperm injection was used in all single-gene disorders. Appropriate in situ hybridisation fluorescence probes were used in chromosome rearrangement and X-linked cases and polymerase chain reaction was used in single-gene disorders. All pregnancies were followed till delivery.

MAIN OUTCOME MEASURE

Live birth rate per PGD cycle started.

RESULTS

Eighty-six percent of cycles started (283) reached oocyte retrieval and 3743 eggs were collected, of which 2086 fertilised normally (55.7%). Two hundred and fifty cycles (76%) had embryos sutiable for biopsy on day 3 of in vitro culture, 1714 embryos were biopsied, and in 205 cycles (62%), there was at least one unaffected embryo available for transfer, resulting in 90 pregnancies, 68 clinical pregnancies and 58 live birth. The live birth rate was 18% per cycle started, 21% per egg retrieval and 28% per embryo transfer which significantly affected the live birth outcome. Woman age, number of eggs collected and achieving cryopreservation of surplus embryos had no statistically significant effect on treatment outcome.

CONCLUSIONS

The live birth outcome of PGD cycles for serious genetic disorder is modest and is affected by the number of embryos genetically suitable for transfer.

Validation of DNA probes for preimplantation genetic diagnosis (PGD) by fluorescencein situ hybridization (FISH) R1

BACKGROUND

Preimplantation genetic diagnosis (PGD) by fluorescence in situ hybridization (FISH) is being employed increasingly by medical centers and private companies. Validation of any clinical assay, particularly one with novel applications such as PGD by FISH, is of critical importance in the clinical setting. This importance is recognized by both the College of American Pathologists (CAP) and the American College of Medical Genetics (ACMG), who recommend validation of FISH assays in the clinical setting. Validation of FISH assays for PGD is especially significant, as only one or two cells (blastomeres) will be available for testing of a given embryo.

METHODS

We have developed validation protocols for a variety of FISH assays, including sex identification, structural chromosomal aneusomy, and aneuploidy screening with the Vysis, Inc., PGT probe panel.

RESULTS

Our validation results show good individual performance of commercially available probes, and decreasing overall efficiency as the number of probes included in an assay increases.

ESHRE PGD Consortium data collection IV: May–December 2001

The ESHRE PGD Consortium was formed in 1997 to survey the practice of preimplantation genetic diagnosis (PGD). Since then, three reports have been published giving an overview on PGD from an ever-increasing number of centres and reporting on an increasing number of PGD cycles and pregnancies and babies born after PGD. After these initial influential publications, important shortcomings were identified primarily on the method of data collection, i.e. with Excel spreadsheets, and in the timing of the collection (cycles were collected in a different time frame from pregnancies and babies, making the follow-up of cycles very difficult). This is why the Steering Committee has made a major investment in developing and implementing a new database in FileMaker Pro 6. It was also decided that cycles would be collected from one calendar year, as well as the pregnancies and babies ensuing from that particular calendar year. This gave us the opportunity to take a closer look at the data collected earlier, and to attempt to improve their quality. This is a report on the corrected data from the first three data collections (I-III) as well as the result of the last data collection (IV) that was completely carried out using the new database.