Preimplantation Genetic Testing in IVF

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Questions and Answers

What is the main purpose of Preimplantation Genetic Testing for Aneuploidies (PGT-A)?

To ensure genetic compatibility between sperm and egg

To detect embryos with chromosomal abnormalities before transfer (correct)

To increase the number of embryos available for transfer

To enhance the viability of all embryos created in IVF

How many chromosomes does a typical human embryo have after fertilization?

48 chromosomes

23 chromosomes

46 chromosomes (correct)

44 chromosomes

Which of the following is a common chromosomal abnormality that can occur?

Turner syndrome, caused by one missing X chromosome

Klinefelter syndrome, caused by an extra X chromosome in males

Down's syndrome, caused by an extra copy of chromosome 21

All of the above (correct)

Which groups are at increased risk for embryo aneuploidy?

Women over the age of 38 and couples with balanced structural rearrangements Signup and view all the answers

What does Smart PGT-A specifically help determine during IVF?

It identifies the embryos with the highest chance of implantation Signup and view all the answers

Which statement about normal embryos and chromosomal abnormalities is true?

Most chromosomally abnormal embryos are indistinguishable from normal embryos visually. Signup and view all the answers

What is the consequence of transferring an embryo with chromosomal abnormalities?

It can lead to miscarriages or complications such as fetal death. Signup and view all the answers

What is one possible outcome for embryos with low-level mosaicism compared to those with aneuploidies?

They have a similar risk of miscarriage as euploid embryos. Signup and view all the answers

Which of the following statements is true regarding the PGT-A test?

There is a chance of a misdiagnosis, including false negatives. Signup and view all the answers

What complication might arise due to the presence of mosaicism in an embryo?

It can cause a diagnostic error in chromosome assessment. Signup and view all the answers

Which characteristic is typically associated with embryos reported as euploid?

They may still have chromosomal abnormalities in unbiopsied cells. Signup and view all the answers

Which of the following is true regarding high-level mosaic embryos?

They generally present lower implantation rates than euploid embryos. Signup and view all the answers

What is the primary benefit of PGT-A in the context of pregnancies?

It increases the chance of having a healthy baby and reduces miscarriage risk. Signup and view all the answers

What is the purpose of the MitoScore test?

To assess mitochondrial DNA in embryos for implantation potential. Signup and view all the answers

What does Smart PGT-A Plus add to the standard PGT-A process?

An assessment of ploidy and quality control analysis. Signup and view all the answers

Which phase occurs before embryo biopsy during the PGT-A process?

In vitro fertilization. Signup and view all the answers

Mosaicism in embryos is indicated by which of the following?

A chromosome copy number variation greater than 30% and less than 70%. Signup and view all the answers

Which technique is recommended for collecting sperm during the IVF process?

Intracytoplasmic Sperm Injection (ICSI). Signup and view all the answers

What is a potential risk associated with invasive prenatal testing methods?

Increased risk of miscarriage. Signup and view all the answers

At what stage can embryo biopsy be performed?

At day 3 or during the blastocyst stage (day 5-7). Signup and view all the answers

What is the role of quality control analysis in Smart PGT-A Plus?

To confirm sibling relatedness and check for DNA contamination. Signup and view all the answers

What happens to the cells obtained from an embryo biopsy after cleaning?

They are sent to Igenomix for genetic analysis. Signup and view all the answers

Study Notes

Preimplantation Genetic Testing and IVF

Preimplantation Genetic Testing (PGT-A) is used alongside in vitro fertilization (IVF) to identify embryos with chromosome abnormalities prior to transfer.
Chromosomal abnormalities can lead to abnormal pregnancies, miscarriages, and failed implantation.
Smart PGT-A is the commercial name of PGT-A service offered by Igenomix.

Chromosomes in Humans

Humans have 24 types of chromosomes: 22 autosomal pairs and 2 sex chromosomes (X and Y), totaling 46 chromosomes in most cells.
Fertilization involves the joining of a sperm (23 chromosomes) and an egg (23 chromosomes), creating a 46-chromosome embryo.
Common chromosomal abnormalities can lead to conditions such as Down's syndrome, caused by an extra copy of chromosome 21.

Causes of Chromosomal Abnormalities

Increased risk of chromosomal abnormalities associated with:
- Women over 38 years
- Severe male factor infertility
- Balanced structural rearrangements in parents
- Errors during cell division
Abnormal embryos often appear normal under microscopic examination, necessitating genetic testing for proper assessment.

Benefits of PGT-A

PGT-A reduces miscarriage risks, increases implantation rates, and enhances the likelihood of having a healthy baby.
Certain chromosomal abnormalities can result in live births with severe health conditions detectable via non-invasive prenatal testing.

MitoScore and Smart PGT-A Plus

MitoScore test evaluates mitochondrial DNA (mtDNA) to differentiate euploid embryos with higher reproductive potential from those with lower potential.
Smart PGT-A Plus incorporates ploidy assessment to identify abnormalities like triploidy and haploidy, which hinder normal development.

PGT-A Process Overview

PGT-A involves three main phases:
- IVF cycle to create embryos
- Embryo biopsy for genetic analysis
- Transport of biopsied cells to Igenomix for evaluation.
Intracytoplasmic Sperm Injection (ICSI) is recommended for fertilization; abstinence from intercourse is advised around embryo transfer.

Embryo Biopsy Techniques

Embryo biopsies can be performed at specific developmental stages:
- Day 3 (blastomere biopsy): Removal of one cell.
- Day 5-7 (trophectoderm biopsy): Multiple cells are collected from a blastocyst.
Embryos may be vitrified (frozen) after biopsy during the testing waiting period.

Result Analysis and Mosaicism

Biopsied cells undergo DNA amplification followed by analysis using Next Generation Sequencing (NGS).
Mosaicism is present when an embryo contains both normal and abnormal genetic cells, classified based on chromosome copy number variation.

Diagnostic Errors and Challenges

PGT-A testing may yield false negatives or positives, with an estimated 1-2% chance of misdiagnosis.
Reasons for discrepancies may include mosaicism, human error, or contamination.
In case of spontaneous conception, the genetic status may differ from that of the tested embryo.

Consent forms for PGT-A must be signed by intended parents (IPs) prior to beginning IVF.
Signed consent forms should be returned via email and maintained in patient records for future reference.

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Description

This quiz explores Preimplantation Genetic Testing (PGT-A) used in conjunction with in vitro fertilization (IVF). Learn about the significance of detecting chromosomal abnormalities in embryos and how it influences decision-making in embryo transfer. Discover the implications of PGT-A for successful pregnancies.