Severe combined immunodeficiency (SCID): from the detection of a new mutation to preimplantation genetic diagnosis.

PURPOSE: To describe the identification of a new mutation responsible for causing human severe combined immunodeficiency syndrome (SCID). In a large consanguineous Israeli Arab family, this served as a diagnostic tool and enabled us to carry out preimplantation genetic diagnosis (PGD). We also demonstrated that PGD for homozygosity alleles is feasible. METHODS: We carried out genome-wide screening followed by fine mapping and linkage analysis in order to identify the candidate genes. We then sequenced DCLRE1C in order to find the familial mutation. The family was anxious to avoid the birth of an affected child, and therefore, because of their religious beliefs, PGD was the only option open to them. The embryos were biopsied at day 3, and a single blastomere from each embryo was analyzed by multiplex polymerase chain reaction for the SCID mutation and 5 additional polymorphic markers flanking DCLRE1C. RESULTS: Linkage analysis revealed linkage to chromosome 10p13, which harbors the DNA Cross-Link Repair Protein 1 C (DCLRE1C) ARTEMIS gene. Sequencing identified an 8 bp insertion in exon 14 (1306ins8) of DCLRE1C in all the affected patients; this causes an alteration in amino acid 330 of the protein from cysteine to a stop codon (p.C330X). One cycle of PGD was performed and two embryos were transferred, one homozygous wild-type and one a heterozygous carrier, and healthy twins were born. CONCLUSIONS: Identifying the familial mutation enabled us to design a reliable and accurate PGD protocol, even in this case of a consanguineous family.

Blastocyst culture and transfer: lessons from an unselected, difficult IVF population.

Blastocyst-stage transfer has yielded excellent results in good prognosis IVF patients, but its efficacy in the general IVF population has not been clearly demonstrated. The objective of this study was to compare cleavage-stage and blastocyst-stage transfer in a mixed, general IVF population. In a prospective, quasi-randomized study, 152 patients underwent 164 treatment cycles. Patients were allocated to cleavage-stage (group 1; n = 94) or blastocyst-stage (group 2; n = 70) transfer. Main outcome measures included implantation, clinical pregnancy and live birth rates. Implantation (11.2% versus 15.5%), clinical pregnancy (34% versus 21%) and live birth rates per transfer (21.3% versus 13.8%) and per started cycle (21.3% versus 11.4%) were all comparable for groups 1 and 2, respectively. Logistic regression analysis revealed that blastocyst culture and transfer reduced the odds for pregnancy in the general IVF population and defined a good prognosis group for blastocyst transfer. Introducing blastocyst culture and transfer to all IVF patients is not advantageous. Blastocyst transfer should be offered primarily to good prognosis patients, and this group should be specifically defined in each clinical set-up.

Timing intra-Fallopian transfer procedures.

With the gradual decline in the use of zygote intra-Fallopian transfer (ZIFT), current practice is to offer ZIFT almost exclusively to patients with repeated implantation failure (RIF). For practical reasons, the procedure is sometimes deferred by 1 day and embryo intra-Fallopian transfer (EIFT) is performed. The aim of the present study was to compare the reproductive outcome of ZIFT versus EIFT. In a retrospective analysis, 176 patients who failed in 7.65 +/- 3.7 previous IVF cycles underwent 200 ZIFT and 73 EIFT procedures. Implantation and live birth rates were compared for both groups. Patients in both groups were found comparable for demographic and clinical parameters. Similar numbers of oocytes were retrieved and fertilized in both groups, and 5.2 +/- 1.2 zygotes/embryos were transferred. Implantation and live birth rates (10.5 and 26.5% versus 10.9 and 24.7% for ZIFT and EIFT respectively) were comparable. It is concluded that tubal transfer of zygotes and day-2 cleavage stage embryos are equally effective.

Follicular growth and development under continuous gonadotropin-releasing hormone antagonist administration.

OBJECTIVE: Ovarian follicle and cyst formation have been recognized as an advance phenomenon associated with GnRH agonist administration. With the use of GnRH antagonists, pituitary suppression is immediate and no flare effect and follicle growth are expected. We describe two patients who developed a dominant follicle and presumably ovulated in response to hCG triggering under continuous sole administration of a GnRH antagonist. DESIGN: Case report. SETTING: An IVF unit at a university hospital. PATIENT(S): Two young healthy female patients undergoing IVF because of male-factor infertility. INTERVENTION(S): Continuous daily administration of a GnRH antagonist from menstruation with the aim of achieving ovarian suppression. MAIN OUTCOME MEASURE(S): Endocrine and ultrasound characteristics of follicular growth. RESULT(S): Both patients developed a dominant follicle under sole administration of a GnRH antagonist, accompanied by a gradual rise in serum estradiol and endometrial thickness which culminated in a spontaneous LH surge. Ovulation was triggered by hCG and mid-luteal progesterone levels were suggestive of ovulation. CONCLUSION(S): We describe for the first time the development of a dominant follicle and presumable ovulation under continuous administration of a GnRH antagonist. Serum gonadotropin concentrations indicate that the pituitary failed to suppress in both patients. The exact mechanism of this phenomenon remains to be elucidated.