Genetics and Fertility
Understanding your genetic makeup is crucial in making informed decisions about your fertility and family planning. Our DNA carries instructions for various traits and functions. Occasionally, individuals carry gene mutations that don’t affect them but could be passed to their children.
How Heredity Works
Each person inherits one copy of every gene from each parent. Some genetic conditions are:
- Recessive: Conditions like cystic fibrosis or spinal muscular atrophy manifest when both parents pass on a faulty gene copy.
- Dominant: Conditions such as Huntington’s disease can occur if only one parent passes on the faulty gene.
- X-linked: Conditions like Fragile X syndrome are linked to genes on the X chromosome and can be passed on even if only one parent is a carrier.
Genetic Carrier Screening
Carrier screening is performed on the partners (or donors) and identifies if you carry gene variants (“mutations”) that could cause serious inherited conditions in your children. It’s typically offered before pregnancy or at the start of fertility treatment. Many carriers will not have a family history suspicious for genetic disease and most are healthy and unaware of their status. However, if both partners are carriers of the same condition, they have a significant risk for having children affected by this genetic disease. Options for family building in this situation include IVF with PGT, using donor gametes, prenatal diagnosis or adoption.
Source: RACGP. Reproductive carrier screening
Preimplantation Genetic Testing (PGT)
PGT involves testing embryos for specific genetic conditions or chromosomal abnormalities before implantation during IVF. Types include:
- PGT-A: Screens for chromosomal abnormalities – primarily done from mid-30s and onwards, to reduce Down syndrome and miscarriage risk.
- PGT-M: Tests for specific inherited conditions – performed when partners are known to have gene mutations that are likely to result in disease.
- PGT-SR: Detects structural rearrangements in chromosomes – performed if partners have a chromosomal rearrangement which may contribute to miscarriage or other complications.
Source: Fertility Society of Australia and New Zealand – Preimplantation Genetic Testing
Frequently Asked Questions
What is the difference between carrier screening and embryo testing?
Carrier screening assesses parents’ genes for inherited conditions, while embryo testing (PGT) examines embryos for specific genetic issues before implantation.
Is genetic testing safe?
Yes. Carrier screening involves blood or saliva samples. Embryo biopsy for PGT is a well-established and safe technique.
Should both partners undergo carrier screening?
This will depend on whether a “core” 3-gene screen or an expanded test of hundreds of genes is being performed. In a core screen, the female partner is ordinarily tested, with the male being tested subsequently if she is found to be a carrier, while in expanded panels both partners are tested in parallel.
Is genetic testing covered by Medicare?
Some tests may be covered, but many, including expanded carrier screening and PGT, may incur out-of-pocket costs.
Can genetic testing be done if I'm already pregnant?
Yes. In the event that genetic screening finds that you are at risk of a child with genetic disease, prenatal testing options are available, but preconception testing offers more reproductive choices so this should be the preferred option.