Reproductive carrier screening
- Reproductive carrier screening aims to identify whether a couple is at risk of having a child with a serious genetic condition.
- It is usually undertaken prior to conception but can also be undertaken early in pregnancy.
- There are options available if reproductive carrier screening identifies a couple that has a greater risk than normal of having a child with a serious genetic condition.
Reproductive carrier screening aims to identify whether a couple is at risk of having a child with a serious genetic condition.
Reproductive carrier screening looks at the genes for a range of X-linked and autosomal recessive conditions. Often the mother is screened first and, the father will only be screened if any disease-causing variations are identified in the mother’s screened genes.
Reproductive carrier screening is usually undertaken prior to conception but can also be undertaken early in pregnancy. This is why it is sometimes called pre-conception carrier screening.
Where reproductive carrier screening identifies a couple that has a greater risk than normal of having a child with a serious genetic condition, a couple may wish to pursue conception by in vitro fertilisation and undergo pre-implantation genetic testing (PGT) to identify embryos for implantation that do not have the genetic condition. Couples who are already pregnant may wish to test their fetuses for the identified condition they both carry via prenatal testing of fetal cells collected through chorionic villus sampling or amniocentesis.
Reproductive carrier screening is only available privately or as part of research. This means there will be a cost associated with such testing. You should discuss this with your healthcare provider.
What is a genetic carrier?
Genes come in pairs. Everyone inherits one copy of each pair from their mother and the other copy from their father. A genetic carrier has inherited a normal gene from one parent and a faulty (mutated) copy of the gene from another parent. A carrier does not usually show traits or symptoms of the genetic condition because the healthy gene is dominant. There are different ways this can occur.
Autosomal recessive conditions
If two carriers for the same disease become pregnant, there is a 1 in 4 chance that the child will have two copies of the faulty gene (one from each parent) and be affected by the genetic condition.
Autosomal recessive conditions include:
- cystic fibrosis
- thalassaemia (an inherited blood disorder that causes your body to have less hemoglobin)
- spinal muscular atrophy.
X-linked recessive conditions
Humans have two sex chromosomes that determine a person’s biological sex. Females have two X chromosomes and males have one X and one Y chromosome. A woman who is the carrier of an X-linked condition, may not be affected by the genetic change in one X chromosome because she has another, healthy chromosome that masks the condition. However, there is a 1 in 2 chance that her male children will be affected by the condition as they only have one copy of the X chromosome.
X-linked conditions include:
- fragile X syndrome
- Duchenne muscular dystrophy
- haemophilia.
McKenzies Mission project
MacKenzies Mission (external site) is a research study that is investigating the best way to deliver a national reproductive screening program in Australia. The study will provide reproductive genetic carrier screening to up to 10,000 eligible couples and provide prospective parents with information on the likelihood that they will have a child with a severe genetic condition.
Where to get help
Last reviewed: 31-05-2022
Acknowledgements
Reproductive Technology Unit