Fertility Blog

ASRM Updates 2008 -- Update 2

Fertility Flash. Among those attending the conference from PFC were Dr. Philip Chenette and Dr. Isabelle Ryan and Peggy Orlin, MFT. Their reviews cover the following topics: Update #1: Ovarian Stimulation Techniques, Update #2: PGD and Aneuploidy Screening Techniques, Update #3: Egg Freezing, Update #4: Acupuncture, and Update #5: Men and ART. Update #2: PGD and Aneuploidy Screening Techniques Preimplantation genetic diagnosis (PGD) has been one of the hallmark technologies of modern reproductive medicine. The ability to look inside a cell, beyond its visual appearance to the actual genes controlling the cell, has provided insight into the workings of the embryo and a valuable clinical tool to improve fertility care. The most common use of PGD is to count chromosomes using FISH probes. Using labels that glow under ultraviolet light, a limited number of chromosomes can be identified and counted. Missing or duplicated chromosomes are indicators of abnormalities in the embryo, a condition known as “aneuploidy.” FISH has a significant error rate, and while clinically useful, results must be interpreted with caution. A new technique discussed at the ASRM meeting is SNP analysis. SNPs are common tags in DNA that can be measured by automated systems. Microarrays of thousands of SNPs have been prepared that provide a clear picture of the chromosome structure of a cell. Microarray-based aneuploidy screening has excellent reliability and accuracy, and holds enormous promise for identifying genetically normal embryos. This study represents the first validated method of analyzing the entire set of chromosomes in a single cell. Stay tuned for more on this exciting technology. Array CGH uses thousands of very small DNA probes along with computer software to describe the structure of DNA in a single cell. A very sensitive test, it is fast enough to be used during an IVF treatment cycle, and far more accurate than conventional fluorescent probe (FISH) analysis. Array CGH may lead to improved IVF outcomes as embryos containing an error in any chromosome can be detected, which would allow better selection of healthy embryos. PGD has proven useful for the treatment of recurrent miscarriage. In an analysis of 279 patients with recurrent miscarriage (women who had previously experienced 3-5 miscarriages), researchers in New Jersey found an improved miscarriage rate of 19.5% after PGD versus their 40.9% expected rate. Philip Chenette, MD