# PGT-M

> Citation bundle for PGT-M on The Treatment Registry.
> URL: https://thetreatmentregistry.com/procedures/pgt-m
> Bundle URL: https://thetreatmentregistry.com/api/citations/procedures/pgt-m

- Category: ivf-fertility

## Description

Preimplantation genetic diagnosis is the genetic profiling of embryos prior to implantation, and sometimes even of oocytes prior to fertilization. PGD is considered in a similar fashion to prenatal diagnosis.

## Overview

PGT-M (preimplantation genetic testing for monogenic disorders) is the genetic profiling of embryos before implantation to detect a specific inherited single-gene disease, so that only embryos free of the known disorder are transferred. It is an application of preimplantation genetic diagnosis and, because it needs embryos to test, is an adjunct to assisted reproductive technology that requires in-vitro fertilisation to obtain the oocytes or embryos. A key advantage is that, by selecting unaffected embryos before pregnancy begins, it can avoid the need for selective abortion, making it highly likely that the baby will be free of the disease under consideration. PGT-M is used for couples known to carry single-gene (monogenic) disorders, including autosomal recessive, autosomal dominant and X-linked conditions, as well as certain chromosomal structural rearrangements such as balanced translocations. Among the conditions frequently tested are autosomal recessive diseases such as cystic fibrosis, beta-thalassemia, sickle cell disease and spinal muscular atrophy type 1, and dominant conditions such as myotonic dystrophy, Huntington's disease and Charcot-Marie-Tooth disease. Embryos are generally sampled by biopsy at the blastocyst stage, around day 5 or 6 of development, which is gentler on the embryo than earlier cleavage-stage biopsy, and the DNA is analysed for the specific mutation. Unlike aneuploidy screening, which counts chromosomes, PGT-M looks for a defined genetic mutation in couples at known risk. As an invasive test performed on the embryo, it requires serious consideration.

## Common risks

- Damage to the embryo during the biopsy, which can destroy the embryo
- Loss of embryos during freezing and thawing (about 20% of thawed embryos do not survive)
- Lower live-birth rate reported with cleavage-stage biopsy in women of advanced maternal age
- Increased perinatal death rate reported in multiple (twin or higher-order) pregnancies

## FAQs

### What is PGT-M?

PGT-M is preimplantation genetic testing for monogenic disorders. It profiles embryos created through IVF to detect a specific inherited single-gene disease, so that only embryos free of the known disorder are transferred.

### What conditions can PGT-M test for?

It is used for single-gene disorders, including autosomal recessive, dominant and X-linked conditions, and some chromosomal rearrangements. Frequently tested conditions include cystic fibrosis, beta-thalassemia, sickle cell disease, spinal muscular atrophy, myotonic dystrophy and Huntington's disease.

### How is PGT-M different from PGT-A?

PGT-M looks for a specific inherited gene mutation in couples at known risk, whereas PGT-A screens for an abnormal number of chromosomes (aneuploidy). PGT-M targets a defined mutation rather than counting chromosomes.

### Does PGT-M require IVF?

Yes. Because embryos are needed for testing, PGT-M is an adjunct to assisted reproductive technology and requires in-vitro fertilisation to obtain the oocytes or embryos to be evaluated.

### Does PGT-M ensure a healthy baby?

When used to screen for a specific genetic disease, it makes it highly likely that the baby will be free of the disease under consideration, and it can avoid the need for selective abortion. It tests only for the specific disorder being screened.

### What are the risks to the embryo?

The biopsy is invasive and can damage or destroy the embryo. Embryos can also be lost during freezing and thawing, with about 20% of thawed embryos not surviving, and some studies report poorer outcomes with cleavage-stage biopsy and in multiple pregnancies.