FISH for pre-implantation genetic diagnosis

Area of Science:

• Reproductive Medicine
• Human Genetics
• Molecular Biology

Background:

• Pre-implantation genetic diagnosis (PGD) is an alternative to prenatal diagnosis for selecting embryos from assisted reproduction technology (ART) cohorts.
• Indications for PGD include familial monogenic diseases, carrier status for chromosome rearrangements, recurrent miscarriages, and infertility.
• Embryos are typically biopsied on day 3 post-fertilization, with a single cell analyzed for genetic status.

Purpose of the Study:

• To describe the application of Fluorescence In Situ Hybridization (FISH) for single-cell analysis in PGD.
• To detail the selection of appropriate DNA probes for FISH in PGD.
• To outline methods for assessing FISH test performance, blastomere spreading, and signal scoring in a clinical setting.

Main Methods:

• Fertilization of oocytes via in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI).
• Biopsy of pre-implantation cleavage-stage embryos (day 3) for single-cell genetic testing.
• Application of Fluorescence In Situ Hybridization (FISH) using target-specific DNA probes on biopsied cells.

Main Results:

• FISH is effective for detecting chromosome imbalance in rearrangements and selecting embryos for X-linked diseases.
• FISH-based screening for sporadic chromosome aneuploidy (PGD-AS) is not recommended due to low predictive accuracy.
• The chapter details probe selection, analytical performance assessment, and FISH procedures for clinical PGD.

Conclusions:

• PGD, utilizing techniques like FISH, is crucial for genetic screening of embryos in ART.
• FISH is a valuable tool for specific genetic and chromosomal analyses in PGD, but not for general aneuploidy screening.
• Optimized FISH protocols are essential for accurate genetic diagnosis in clinical PGD settings.