PDG-Lifescreen — Preimplantaion Genetic Diagnosis

On July 5th 2011, the first case of a healthy baby boy conceived by the father with with nonmosaic Kleinfelter’s syndrome (extra X chromosome) born in Russia was registered. The child was conceived via IVF program with PDG inclusion at MAMA Clinic under the guidance of Chief Reproductive Therapist Dr. Victoria Zaletova. This case marked a breakthrough on Russian reproductive medical services market. The process of treatment and PDG application was described in detail and the summary of it later published in “Reproductive Problems” Magazine (2012, issue # 1). The corresponding scientific report was presented at 94th Annual Meeting of ENDO in Houston, USA, in 2012 as well as PDGIS International Conference in Istanbul, Turkey, in 2013.

Preimplantation Genetic Diagnosis (PDG), also known as Embryo Screening, is a newer state-of-the-art bio-molecular procedure, generally recommended to detect numerical and structural anomalies in the genetic structure of embryos, as well as conditions caused by single gene defects. When embryos are affected by certain chromosomal or genetic conditions, these can prevent implantation to the uterine lining, lead to pregnancy loss, or else result in the birth of a child with physical problems and/or mental retardation. PGD helps preventing adverse outcomes by identifying affected embryos while they are developing in vitro and before they are transferred to the uterus. At MAMA Clinic, we include PDG-Lifescreen in IVF programs whenever the reason to recommend it is detected. The procedure is usually performed on 3d to 5th day of embryo development.

PDG method practiced at MAMA Clinic is known as FISH (Fluorescence In Situ Hybridization). This technique was originally developed by biomedical researches in early 80s. FISH uses fluorescent probes that bind only to those parts of the chromosome with which they show a high degree of sequence complementarity. The first step is to prepare short sequences of single-stranded DNA that match a portion of the gene the researcher is looking for. For this purpose we separate the nuclei from the embryo cell, which contains all genetic data. These are called probes. The next step is to label these probes by attaching one of a number of fluorescent dye. As the result of FISH analysis, the specialists receive an image map of embryo nuclei, where the target particles are depicted as colored spots, which complete the description of the chromosomes state and possible disorders.

FISH is primarily used for detecting numeric chromosome pathologies and mutations, which lead to most common embryo pathologies. At MAMA Clinic, we are qualified and equipped to detect not only the three major aneuploidies (X, Y and 21), but we also perform the unique PDG-Lifescreen diagnostic method, which enables to simultaneously detect 9 types of aneuploidies (X, Y, 21, 13, 16, 18, 22, 8, 9). The application of this elaborate technique allows detecting and preventing the following disorders:

  1. Damages in course of preimplantation embryo development with further implantation pathology. This mostly refers to monosomia (a missing chromosome in the pair), which is the most severe chromosome numeric pathology: most embryos suffering from it die before being implanted.
  2. Early stage miscarriages. Over 50% of chromosome anomalies, discovered in spontaneous abortion tissue are those of trisomy types (extra chromosome in a pair). As a rule, such disorders exclude the chances of normal fetus development and inevitably lead to early miscarriages. The most common type of trisomy anomalies is that of the 16th chromosome, which is detected in over 30% of trisomies. This is why we have included 16th chromosome examination in the basic package of PGD-Lifescreen at MAMA Clinic.
  3. Genetic Chromosome Disorders. As it was mentioned above, most cases of trisomy are incompatible with normal pregnancy course and lead to early miscarriages. Yet, some trisomy anomalies do not provoke spontaneous abortion but result in the birth of a child with physical problems or/and mental retardation. These can also be detected by PDG:

    • Trisomy 21 (Down Syndrome)
    • Gender Trisomy (Y and X)
    • Trisomy 13 (Patau Syndrome)
    • Trisomy 18 (Edwards Syndrome)
    • Trisomy 22 (Cat Eye Syndrome)
    • Trisomy 8 (Warkany Syndrome)
    • Trisomy 9

Summing up the above said, at MAMA Clinic we practice wide range of Preimplantation Generic Diagnosis tools allowing to detect numeric chromosome disorders, which lead to spontaneous abortions in some cases and birth or unhealthy child in others. This wide specter of PDG services helps us provide all the service necessary for patients with certain genetic pathologies seeking to conceive and give birth to genetically their own healthy child.

Julia Zaikova