Pre-implantation Genetic Diagnosis (PGD)

Monash Reproductive Pathology and Genetics has performed over 1000 PGD cases, with 8% of the world's PDG births occuring at Monash IVF. Fluorescent In Situ Hybridisation (FISH) pregnancy rates in 2006 are 40% per embryo transfer.

Preimplantation Genetic Diagnosis (PGD) is a reproductive option for couples at risk of passing on a specific genetic disease or chromosomal imbalance to their children.  PGD involves screening IVF generated embryos for genetic disease prior to embryo transfer.  This provides the opportunity to determine the genetic status of an embryo before a pregnancy is established.  Couples choose PGD over prenatal diagnosis for many reasons including objection to termination of pregnancy, loss of a child from the genetic disease, repeat implantation failure or repeat miscarriage.

PGD testing may be appropriate for:

• Couples at risk of passing a single gene disorder on to their children
• Couples at risk of having children with a particular X-linked disorder
• Couples where one partner carries a balanced chromosomal rearrangement
• Couples with advanced maternal age (>36)
• Couples who have experienced repeated miscarriage
• Couples who have experienced repeated IVF failure
• Couples who have previously had a pregnancy with a chromosomal abnormality

Genetic counselling is an important step to ensure that PGD is the right option for you. Please refer to our fact sheet entitled "Preimplantation Genetic Diagnosis" for further information regarding the PGD procedure.

What does PGD involve?

All couples requesting PGD must first undertake an IVF cycle to stimulate the woman’s ovaries to produce a number of eggs.  These eggs are collected and fertilised using the male partner’s sperm.  The resulting embryos are cultured in the laboratory.  Embryo biopsy is performed on Day 3 after egg collection.  Embryos that have developed to at least 5 cells are suitable for biopsy.  A hole is drilled in the outer shell of the embryo and 1 or 2 cells are removed for analysis.

The Preimplantation Genetic Diagnosis (PGD) program at Monash IVF

Monash IVF has offered PGD as a clinical service since 1996, and is one of the few centers in Australia that specializes in this area of reproductive medicine.  Monash IVF has performed over 2300 PGD cycles and has proven high success rates.  All of our PGD testing is performed in house at Monash IVF Clayton by a highly specialised genetics team.  The Monash IVF genetics team includes many highly qualified experts in PGD, ensuring the highest quality of care to patients.  Treatment is available in a timely fashion and couples are not required to wait before the team can assess the possibilities of designing a unique genetic test.  The genetics team is responsible for providing a specialised PGD service not only to our own patients, but also to patients undergoing IVF cycles at fourteen different IVF clinics throughout Australia and New Zealand.  While the main PGD laboratory is located in Clayton, Melbourne, Australia, embryo biopsy can be performed away from the genetics laboratory and the embryonic cells (called blastomeres) sent by courier to Clayton.  Centralising the genetic testing enables clients to access the highest levels of expertise without having to leave their home state.

PGD for single gene disorders

PGD is a viable option for couples at risk of passing on a specific single gene disorder to their child, and significantly increases the chance of having a healthy baby.  Monash IVF has developed PGD tests for the following single gene conditions:

Achondroplasia	Hypophosphatemic Rickets
Adrenoleukodystrophy	Infantile Batten Disease
Alagille Syndrome	Laing Distal Myopathy
Albright Hereditary Osteodystrophy	Larsen Syndrome
Alpers Syndrome	Lesch Nyhan Syndrome
Amyloidosis	Lissencephaly
Amyloidosis	Lymphoproliferative Syndrome
Aniridia	Marfan Syndrome
Beta-Thalassaemia	Medium Chain Acyl CoA Dehydrogenase Deficiency
BrCa1	Metachromatic Leukodystrophy
BrCa2	Multiple Endocrine Neoplasia, Type 1
Bruton's X-linked Agammaglobulinaemia	Multiple Endocrine Neoplasia, Type 2a
Bullous Ichthyosiform Erythroderma	Myotonic Dystrophy (MD)
Cadasil	Myotubular Myopathy
Cardiomyopathy	Neurofibromatosis, Type 1
Charcot-Marie-Tooth, Type 1A	Neurofibromatosis, Type 2
Charcot-Marie-Tooth, Type 1B	Optic Atrophy
Chronic Granulomatous Disease	Osteogenesis Imperfecta
Congenital Amegakaryocytic Thrombocytopenia	Phaeochromoctoma
Crouzon Syndrome	Polycystic Kidney Disease
Cystic Fibrosis	Propionic Acidemia
Deafness (connexin 26)	Retinitis Pigmentosa
Diastrophic Dysplasia	Retinoblastoma
Escobar Syndrome	Rhesus D
Familial Adenomatous Polyposis	Severe Combined Immune Deficiency
Fragile X	Smith Lemli Opitz Syndrome
Haemophilia B	Spinal Muscular Atrophy (SMA)
Hereditary Diffuse Gastric Cancer	Spinocerebellar Ataxia, Type 2
Hereditary Multiple Exostoses	Spinocerebellar Ataxia, Type 3
Hereditary Non-Polyposis Colorectal Cancer	Spinocerebellar Ataxia, Type 6
Hereditary Sensory Neuropathy	Spinocerebellar Ataxia, Type 7
Huntington’s Disease	Tay Sachs Disease
Hydrocephalus	Tuberous Sclerosis
Hypertrophic Obstructive Cardiomyopathy	Von Hippel-Lindau
Hypohidrotic Ectodermal Dysplasia	Wiskott-Aldrich Syndrome
Hypophosphatasia	Zellweger Syndrome

Monash IVF has been responsible for developing new PGD technologies and is able to develop tests for other genetic disorders upon request.  If the disorder you are interested in is not listed please contact Monash IVF for further information.  You may also like to refer to our fact sheet entitled “Preimplantation Genetic Diagnosis for single gene disorders” for more specific information about this type of testing. 

Sex selection for X-linked disorders

X-linked disorders (eg: Haemophilia A, Myotonic dystrophy and OCT deficiency) are caused by mutations on the X chromosome.  As the X chromosome is one of the sex chromosomes, the possibility of a particular embryo being affected is dependent upon whether the embryo is male or female.  This type of testing involves identifying the sex of the embryo rather than the particular genetic condition.  For most conditions, female embryos (which can be normal or carriers of the condition) will be selected for transfer.  Male embryos (which can be normal or affected by the condition) will be frozen if they reach the appropriate developmental stage.  Please refer to our fact sheet entitled “Preimplantation Genetic Diagnosis with sex selection for X-linked genetic disorders” for more specific information about this type of testing. 

PGD for translocations or other balanced chromosomal rearrangements

PGD may be available to couples where one partner carries a balanced chromosomal rearrangement, such as a translocation.  Translocation carriers may experience difficulties with reproduction due to the generation of chromosomally unbalanced embryos.  As a result, these couples may have difficulty conceiving or may experience multiple miscarriages.  This type of testing involves analysis of the chromosomes involved in the translocation and can distinguish between normal/balanced embryos (which have the potential to produce a healthy baby) and unbalanced embryos (which would fail to implant, miscarry or result in an affected baby).  Monash IVF has developed PGD tests for over 180 couples in which one partner carries a balanced translocation.  Please refer to our fact sheet entitled “Preimplantation Genetic Diagnosis for translocations” for more specific information about this type of testing. 

PGD with aneuploidy screening

Chromosomal aneuploidy is a term used to describe an irregularity in chromosome number (ie: the loss or gain of a specific chromosome).  Normal embryos should inherit one copy of each chromosome from each parent and therefore have two copies of each chromosome.  Some embryos can have an irregular number of chromosomes due to errors in cell division.  This can result in implantation failure, miscarriage, or the birth of an affected child.  Couples at increased risk of producing aneuploid embryos may experience infertility.  PGD testing can be used to screen for the most common chromosome irregularities (involving chromosomes X, Y, 13, 15, 16, 17, 18, 21 and 22).  This testing may be appropriate for:

• Couples with advanced maternal age (>36 years)
• Couples who have experienced repeated miscarriage
• Couples who have experienced repeated IVF failure
• Couples who have previously had a pregnancy with a chromosomal abnormality

Please refer to our fact sheet entitled “Preimplantation Genetic Diagnosis with Aneuploidy Screening” for more specific information about this type of testing.

How do I get started?

If you are interested in PGD, please discuss this procedure with your IVF doctor or with a member of the genetics team at Monash IVF.  Genetic counselling may help you and your partner decide whether or not PGD is the right option for you.  Monash IVF offers consultations with a clinical geneticist and genetic counsellor, whose professional expertise enable them to thoroughly review your genetic history, arrange further clinical and DNA testing to confirm genetic status and offer guidance and support at all times to alleviate any anxiety.  Following counselling, you should be aware of the relative risks of embryo screening and possible outcomes, placing you in a sound position to make an informed decision about PGD.  Please contact us for additional information or to make an appointment.