Search

Objective: To report a clinical pregnancy after rebiopsy and vitrification of blastocysts following allele dropout (ADO) of biopsied day 3 embryos. Design: Case report. Setting: Private center. Patient(s): Thirty-year-old woman and her 33-year-old husband who carries the single-gene condition paraganglioma. Intervention(s): In vitro fertilization with day 3 embryo biopsy–ET–blastocyst biopsy and vitrification–subsequent frozen ET cycle. Main Outcome Measure(s): Results from preimplantation genetic diagnosis and pregnancy results after fresh and frozen ETs. Result(s): Nineteen oocytes were retrieved of which 13 were mature and 12 fertilized. Eleven embryos were biopsied on day 3: two were normal, five were affected, and four exhibited ADO. The two normal blastocysts were transferred, and three of the ADO blastocysts were biopsied and sent for reanalysis. The biopsied blastocysts were vitrified. No pregnancy resulted from the fresh ET. One of the biopsied blastocysts was normal, one received no result, and one exhibited ADO. A singleton clinical pregnancy resulted from a subsequent frozen ET of the thawed biopsied normal blastocyst. Conclusion(s): Rebiopsy and vitrification of blastocysts could be used in cases of ADO or lack of results after day 3 embryo biopsy. [Copyright &y& Elsevier]

Strategies for preimplantation genetic diagnosis (PGD) have become increasingly complex. For single gene disorders it is now usual for several DNA fragments to be simultaneously amplified using multiplex-PCR. This allows redundant diagnostic loci to be analyzed, reducing the chance of misdiagnosis due to allele dropout (ADO). Additionally, hypervariable ‘fingerprinting’ loci can be amplified, revealing the presence of DNA contaminants. Chromosomal screening has also increased in complexity. Current FISH techniques investigate up to nine chromosomes per cell and are offered to an increasingly wide range of patients, including women of advanced reproductive age and those with a history of repeated spontaneous abortion. Technical limitations, which preclude a full assessment of all chromosomes using FISH, have encouraged the development alternative tests. These include nuclear conversion, comparative genomic hybridization (CGH) and the use of DNA microarray ‘chip’ technology. This paper discusses technical innovations that have improved the scope and accuracy of PGD, as well as the emergence of new indications for PGD that are sometimes considered controversial (e.g. HLA-typing). [Copyright &y& Elsevier]