Preimplantation genetic screening: does it help or hinder IVF treatment and what is the role of the embryo?

Abstract

Despite an ongoing debate over its efficacy, preimplantation genetic screening (PGS) is increasingly being used to detect numerical chromosomal abnormalities in embryos to improve implantation rates after IVF. The main indications for the use of PGS in IVF treatments include advanced maternal age, repeated implantation failure, and recurrent pregnancy loss. The success of PGS is highly dependent on technical competence, embryo culture quality, and the presence of mosaicism in preimplantation embryos. Today, cleavage stage biopsy is the most commonly used method for screening preimplantation embryos for aneuploidy. However, blastocyst biopsy is rapidly becoming the more preferred method due to a decreased likelihood of mosaicism and an increase in the amount of DNA available for testing. Instead of using 9 to 12 chromosome FISH, a 24 chromosome detection by aCGH or SNP microarray will be used. Thus, it is advised that before attempting to perform PGS and expecting any benefit, extended embryo culture towards day 5/6 should be established and proven and the clinical staff should demonstrate competence with routine competency assessments. A properly designed randomized control trial is needed to test the potential benefits of these new developments.

A review of, and commentary on, the ongoing second clinical introduction of preimplantation genetic screening (PGS) to routine IVF practice

“…Published reviews in the literature are confirmatory [6,33,34]. PGS utilization to improve pregnancy and miscarriage rates, based on currently available data [1,2,7,9,29,30,35,36] should, therefore, only occur under study conditions, and with appropriate informed consents.…”

The state of “freeze-for-all” in human ARTs

“…In 1990, Handyside et al [42] treated couples with sex-linked disorders through DNA amplification followed by PCR for a specific repeated gene sequence on the Y chromosome. Later, PCR was found to be less effective in determining gender as it produces qualitative and non-quantitative data, which means that test results could confirm sex by highlighting the presence or absence of a specific repeated gene sequence unique to the Y chromosome without providing further information on the existence of an X or Y chromosome [43]. To overcome this disadvantage, fluorescent in situ hybridization (FISH) came along and expanded rapidly to also include somatic chromosomes [44].…”

Blood pressure and anthropometrics of 4-y-old children born after preimplantation genetic screening: follow-up of a unique, moderately sized, randomized controlled trial

“…Furthermore, it is the only study evaluating anthropometrics and received medical care in children born following PGS alone, instead of in a combined group of children born following PGS and PGD. The technical procedures of PGD are similar to those of PGS, but the indication for PGD is to screen for and select embryos against specific genetic diseases in high-risk couples (25). This means that couples undergoing PGD are often fertile, whereas couples undergoing PGS are subfertile.…”