The percentage of abnormal embryos increases with maternal age . This explains why the chance of a pregnancy for older patients is lower . However , once we identify the normal embryo , the chance of pregnancy will be the same for both groups of patients .
What are the benefits of PGT-A ? � Higher implantation rates � Reduce the risk of adverse outcomes in pregnancies � Single embryo transfer that reduces complications associated with multiple pregnancies � Decreased time to pregnancy � Increased cost-effectiveness
Who will benefit from PGT-A ? � Women of advanced age � Women who experienced recurrent implantation failure � Women who had more than one miscarriage � Men with severe infertility
( oligoasthenoteratozoospermia , OATS ) � Couples with previous history of children with aneuploidy � All who should do a routine screening
What is PGT-M ? PGT-M stands for Pre-implantation Genetic Testing for Monogenic Disorder . Similarly to PGT-A , it is a genetic test performed prior to implantation . However this test is a targeted screening of single gene inherited diseases for both rare and more common diseases such as thalassemia , muscular dystrophy , ATRX syndrome and etc . With this , the chance of passing on specific single gene disorder can be reduced or prevented .
What ’ s more , PGT-M can be performed along with Leucocyte Antigen ( HLA ) typing in order to identify embryos that are HLA-compatible for children who need a bone marrow or cord blood transplant .
How is the test performed ? PGT-M requires a preparation test prior to IVF cycle . Genetic counselling with our in-house genetic counsellor will be carried out and family histories will be accessed . DNA samples from the couple and their family member ( s ) will be collected ( blood / saliva ) then tested in advance . Once the preparation is ready , similar to PGT-A , routine IVF is then performed and the subsequent embryos are cultured to the blastocyst stage ( Day 5 & 6 ), at which point several cells are biopsied from the blastocyst . These cells are sent for genetic screening while the blastocyst is cryopreserved for later use .
What are the benefits of PGT-M ? � Reduce the risk of passing on affected gene ( s ) to next generation � Decrease time to pregnancy � Increase cost-effectiveness � Assist in the search of a HLA-compatible donor to the affected child
Who will benefit from PGT-M ? � Couples with a history of pregnancy termination ( s ) due to a serious genetic disorder � Couples who have children with genetic disorders � Couples who want to perform HLA matching � Couples who have a family history of any inherited genetic condition � Couples with inherited mutated gene ( s ) ( pre-marital screening / carrier screening test )
How does PGT-M differ from PGT-A ?
PGT-M Screening of known single gene inherited disease .
( eg . Thalassemia , cystic fibrosis , Marfan syndrome , Muscular dystrophy , Breast cancer , etc .)
Screening of aneuploidies or an abnormal number of chromosomes .
( eg . Down syndrome , Turner Syndrome , Edward Syndrome )
Dr . Aaron Chen Jang Jih Lead Preimplantation Genetic Testing Scientist . Sunfert International Fertility Centre
GlobalHealthAsiaPacific . com ISSUE 2 | 2023