Preimplantation Genetic Testing

for Monogenic Single Gene Defects (PGT-M)

PGT-M, formerly called PGD, is a reproductive technology used with IVF cycles for at-risk couples to determine that an embryo used for transfer DOES NOT contain an inherited genetic disorder; ensuring the disorder is not passed on to their children. PGT-M is performed with PGT-A to select embryos for transfer that are free of genetic disease as well as chromosomally normal.

PGT-M Frequently Asked Questions

Looking for more information on PGT-M at Fairfax Diagnostics? Here are some frequently asked questions.

Inheritable diseases that are generally thought to be caused by mutations in one gene are called single-gene, or Mendelian, disorders. Advances in medical genetics have identified the molecular basis of over 6,000 Mendelian disorders, most of which Fairfax Diagnostics can design a couple-specific test to detect such mutations in their embryos.

Huntington’s Disease
Spinal Muscular Atrophy (SMA)
Cystic Fibrosis (CF)
Duchenne’s Muscular Dystrophy (DMD) (X-linked)
Hemophilia (X-linked)
Fragile-X Syndrome

Who Should Consider PGT-M?

Inherited genetic diseases can be devastating to the families they affect. For couples at risk of having children with such diseases Fairfax Diagnostics can provide services specialized for that couple’s genetic situation. Risk factors include:

Family History

A family history of known single-gene disorders.

Autosomal Dominant Genetic Disorders

Partners who are affected by or carriers of an autosomal dominant genetic disorder such as Marfan Syndrome.

Autosomal Recessive Genetic Disorders

Partners who are affected by or carriers of an autosomal recessive genetic disorder such as Cystic Fibrosis.

X-linked Genetic Disorders

Partners who are affected by or carriers of an X-linked genetic disorder.

Preimplantation Genetic Testing for Monogenic Disorders

In this detailed article by Martine De Rycke and Veerle Berckmoes, the reader can gain insight into the process and advancements in the detection of monogenic disorders and single-gene diseases using PGT-M.

Fairfax Diagnostics PGT Lab

PGT-M Test Design

Our test is custom designed to detect the affected gene and specific mutation, as well as flanking polymorphic markers. This multi-layered approach provides added diagnostic accuracy and is a feature unique to Fairfax Diagnostics. PGT-M cycles are always coupled with PGT-A for chromosomal aneuploidy detection, and due to the complexity of genetic testing for these disorders, patients should have a full consultation with a medical geneticist to determine if this option would fit their family’s needs.

Each couple’s PGT-M test is based on the findings of their genetic reports. Each case is reviewed by the clinical and molecular genetics staff before test development. DNA samples are collected from the couple and any informative family members based on our genetic counselor’s pedigree analysis.

PGT-M is a multi-tiered test designed to (1) identify the molecular lesion associated with the genetic disorder, (2) use ‘linkage analyses’ to ensure that the correct (unaffected) gene is inherited from each parent, and (3) use PGT-A to determine that unaffected embryos are also chromosomally normal to enhance the success of the pregnancy. The PGT-M test is validated using samples from the couple and any informative family members prior to clinical use to ensure accuracy and predict the possible outcomes in individual embryos.

After embryo biopsies are obtained from your embryology lab, DNA from each embryo and controls is subjected to the validated, couple-specific PGT-M test. State-of-the-art molecular technologies are used to determine the genetic and chromosomal status of each embryo as expected from the testing algorithm developed for that couple.

All test results are reviewed by the PGT-M team of clinical geneticists, genetic counselors, and laboratory staff at Fairfax Diagnostics to discuss and confirm all data before a report is issued.

Can PGT-M Be Combined?

Yes, single-gene disorder testing can be coupled with PGT-A for chromosomal aneuploidy detection. In certain circumstances, PGT-M for two different gene disorders can be included in one IVF cycle.

PGT-M Technology

PGT-M at Fairfax Diagnostics uses three levels of resolution for diagnostic accuracy:


Mutation specific targeted PCR and single-base sequencing.


Allele haplotyping using linked short tandem repeats (STR).


Next generation sequencing for 24 chromosome analysis.