Preconception Genetic Testing

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If you are a healthy couple planning on starting a family, it is worth considering ‘preconception genetic testing.’ This is an option, requires out-of-pocket cost and is a personal choice for each couple.

Genes and disease

Our DNA carries millions of different genes, which contribute to all of our own attributes and, sometimes, to inherited disease. A ‘recessive’ gene can be carried through generations of a family without anyone realising. If two healthy people are both ‘carrying’ the same gene, their child may inherit the gene from both parents which results in a disease.  Usually there is no significant family history of this disease and it comes as a complete surprise to the parents.

Testing

There are now tests available to check if you or your partner carry these genes. For some couples this information will help them in planning their family, or seeking IVF options if they choose to. Many couples may choose to only have the female partner tested first, and then proceed with testing the male partner only if there the female partner is found to be a carrier for one of the tested conditions.

The diseases which are most easily tested for are:

Cystic fibrosis (CF)

This affects the lungs and digestive tract, leading to recurrent infections and a shorter life expectancy (currently approximately 38 years old). People with CF require regular, lifelong medical treatment but in recent years their life expectancy and quality of life are improving.

Spinal muscular atrophy (SMA)

SMA is a disease causing gradual and irreversible breakdown of the nervous system, leading to many complications. There is no cure but there are supportive treatment options.

Fragile X Syndrome (FXS)

This is the most common inherited cause for intellectual disability, and can vary from mild to severe. It can also cause learning difficulties, anxiety, autism and other behavioural challenges. There is no cure, but medical and behavioural assistance can improve outcomes.

Testing for these four diseases costs approximately $385. Some pathology companies offer a more comprehensive check for over 300 different gene mutations and inherited conditions. These tests are more expensive, and often a specialist geneticist is needed to help in interpreting and discussing these.

What does it mean if we are carriers?

If one parent is a carrier of the gene, and the other parent is not, there is:

• 0% chance that their child will have the disease

• 50% chance that their child becomes an unaffected carrier

• 50% chance that their child is completely unaffected 

If both parents are found to be carriers of a gene, there is:

• 25% chance that their child will have the disease

• 50% chance their child becomes an unaffected carrier

• 25% chance their child is completely unaffected

In any of these situations, couples can choose to see a genetic counsellor to help explain the situation, and the risks of proceeding with natural conception and pregnancy, or a specialist in IVF, who can help in reducing the risk of passing the disease onto their children.

What if this is too expensive, or we choose not to do the testing?

That’s just fine too. The testing is completely optional and there are many other simple steps you can take to prepare for a healthy pregnancy.

Book in with your GP to discuss how best to prepare for a healthy pregnancy.

Written & collated by Dr Michael Meagher