Pre-implantation Genetic Diagnosis (PGD/PGT-M)
This method allows for the diagnosis of known genetic diseases - of which one or both members of the couple may be carriers or may be suffering - in embryos resulting from in vitro fertilisation, so that only healthy ones may be transferred to the uterus. To that end, when the fertilised ova are at the 8-cell or at the blastocyst stage, an ‘opening’ is made in the shell of the ovum (zona pellucida) under a microscope and with the aid of a laser beam. Through this opening a cell is collected - if the biopsy is performed at the 7- to 8-cell stage - or five to ten cells are collected - at the blastocyst-stage - which are then sent to the genetics lab to be genetically analysed. Thus, monogenetic disorders (e.g., cystic fibrosis, thalassemia), X- chromosome sex- linked disorders (e.g., Duchenne muscular dystrophy, haemophilia) or chromosomal anomalies (e.g. trisomy) can be diagnosed. Judging from the children that have been born to this day, it seems that pre-implantation diagnosis is accurate and safe.