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PGT-M (Preimplantation Genetic Testing for Monogenic Disorders)

Monogenic diseases are genetic disorders caused by a single defective gene that can pass from parents to their children. Monogenic diseases are major causes of various problems including birth defects, early mortality, and disability. It may also affect their family in both psychological and social issues. The inheritance patterns of the mutated gene are different, which it depends on the location of defection or a type of the mutated gene (autosomal recessive, autosomal dominant and X-linked pattern). Therefore, carrier testing (carrier screening) or couple checkup of parents before having a baby would be beneficial.

However, preimplantation genetic testing for monogenic (PGT-M) (as known as PGD) has been developed for patients who are at high risk of inheriting a defected gene to their children. It could be offered to patients who have history of genetic disease or known as being a carrier of any genetic inheritance disease. The PGT-M will be performed to screen the specific defected gene on the embryo in order to help people to avoid the affected child before transferring.

For example, Thalassemia, Hemophillia A or B, Cystic Fibrosis, Duchenne Muscular Dystrophy, Marfan syndrome, and Spinal Muscular Dystrophy are commonly known as inheriting disease among family.

Most of the time PGT-M has been performed under the investigation of mutation within the family which including both husband, wife, their children and their parents or siblings. The more information we can get, the more sensitivity, specificity, and reliability we can analyse together with the genetic results and generate the final report.

Notably, each case of PGT-M would be discussed and evaluated by our PGT-M physician, genetic consultant, and professional laboratory staff to assess the case and recommend the suitable technique for the couple.

Recently, we have two kind of techniques available in our center

A. Karyomapping

This technique is using single nucleotide polymorphisms (SNPs) as a detector. SNPs are spreading along human DNA and there are millions of them and individually different. Even this is an indirect method, the huge number of SNPs (300,000 region) on genome increases the accuracy of analysis. However, SAFE is the first laboratory in Thailand who pursued Karyomapping.

B. Conventional method

Conventional method is a combination of linkage analysis and target mutation method. Linkage analysis will find the connection of anomalies transmission from parents to child while using the well-known Short tendem repeat (STR) method. This technique is using the STR markers which are DNA component and normally different between individuals. While target mutation is used for screen at the specific location of mutation.