Genetics is the study of inherited disorders, some of which may be passed on through families.
Genetic counsellors or clinical geneticists are doctors who specialise in understanding and recognising genetic disorders. They help to determine your chances of having a baby with a genetic disorder or a birth defect.

The role of the genetic counsellor is to ensure that you and your partner or family understand the risks of a particular condition being passed on to your children and the options available to you. This will help you make an informed choice about any future pregnancies.

Why might I be referred to a genetic counsellor?

You may be referred for prenatal genetic testing if you plan to become pregnant and:

• You or your partner have a genetic disorder or birth defect;
• You will be 35 years or more at the time your baby is born;
• You have experienced a stillbirth or multiple miscarriages with no known explanation;
• You have a medical condition such as epilepsy or diabetes that requires that you take medications;
• You, your partner or someone in your family have a child with intellectual disability or developmental delay;
• The baby’s father is your first cousin or another close blood relative;
• You want to know more about testing for genetic conditions which are common for certain ethnic backgrounds (i.e. cystic fibrosis, sickle cell disease, thalassaemia, Tay-Sachs disease);
• You have had a positive prenatal screening test result;
• You have had an ultrasound examination which shows a physical abnormality in the baby;
• You are worried about the chance of having a baby with a birth defect or genetic disease and want to know more about available testing.
• You may also be referred to a genetic counsellor to help reach a diagnosis or exclude a genetic disorder if you have a child with a disability or illness.

What happens at a genetic counselling session?

To try and determine any risk of genetic disorders, the genetic counsellor will draw your family tree. Before attending the session you should speak to your relatives (parents, siblings, aunts, uncles, and grandparents) to find out about any birth defects or chronic illnesses (such as heart disease or diabetes) in either of your families.

The counsellor will discuss any inherited disorders which show up in your family history and the chance of you passing them on to your child. Further tests such as a blood test or amniocentesis may be necessary to reach a confirmed diagnosis of risk.

Typically, a session with a genetic counsellor may last 30-60 minutes but you should take all the time you need to ask questions.

Are all birth defects genetically inherited?

A number of birth defects are inherited but others may be caused by environmental factors such as drug or alcohol abuse, exposure to certain medications or chemicals or certain infections.
The most common birth defects are those that occur due to a combination of factors in the outside environment and some maternal or hereditary traits. However, often the cause of a birth defect is not known for definite.

What are the common birth defects?

Birth defects may be physical or mental and vary in severity. Some may be mild and easily reversible and others may be fatal. It is important to remember that prenatal tests may detect many of these defects but not all.
Birth defects include:

• Cleft lip and palate
• Cystic fibrosis
• Down Syndrome
• Heart defects
• Huntington’s chorea
• Hydrocephalus
• Spina bifida
• Sickle cell anaemia
• Tay Sachs disease
• Thalassemia

What are the advantages of genetic counselling?

One advantage of genetic testing is to help parents prepare for a child with special needs, particularly if there is medical history indicating a greater likelihood of a genetic problem. For many couples the information offered provides reassurance in the face of uncertainty and gives them a sense of control over the situation.

If you have received abnormal test results or have evidence of a genetic condition, a genetic counsellor can be of great benefit to you. The role of the counsellor is to provide an unbiased, complete and accurate view of the situation, the nature of the birth defect being investigated and what in practical terms it will mean to you, your family and all concerned. He or she will explain the outlook for a child with a particular abnormality and describe what treatments may be necessary at birth and throughout the child’s life.

The counsellor will not try and steer you into one decision or another – their role is to provide you with the information to make your own, informed choice.