Very few couples will need genetic counselling but if you do, the main aim is to discover how great a risk you run of passing on an inheritable disease to your child. Perhaps you're worried because you or your partner have a blood relative (including, perhaps, a previous child) who has suffered from an inheritable disorder. Depending on what you find out, a genetic counsellor will also help you and your partner decide whether or not to go ahead with trying to conceive.
How genetic counselling works
When you first meet a genetic counsellor, you'll be asked lots of questions about your health, and about your family background. Take along as much information as you can and be prepared for the whole project to take some time. The advice you'll be given at the end of it depends on a precise diagnosis of the disease (what it is and why it happened), and on the making of a family tree, with details of all blood relationships and any diseases suffered.
Your counsellor will assess the degree of risk in your case and help you make an informed decision. If there's a small risk, you may decide to go ahead and try for a baby. If the risks are very great, you might prefer not to take that chance.
For many genetic disorders, such as sickle-cell anaemia or Tay-Sachs, prospective parents can be checked to find out if they are carriers. This can be done by seeing evidence of the disease itself on a blood sample; by looking for the product of the disease, such as the proteins that are present in Tay-Sachs; or by flagging a gene or chromosome. Flagging is a sophisticated technique that's used to find out if a fragment of DNA attaches itself to the patient's chromosome. If it does, the gene, and therefore the disease, is present; if not, it's absent. In most diseases, though, more than one gene is involved, so it can be difficult to check all the elements involved.
If a couple has already had a child with a congenital defect, the counsellor will first rule out any possible causes that aren't inherited, for example rubella. Other possible causes such as exposure to radiation, drugs, or injury will also be looked at.
Sometimes it can be difficult to pinpoint the exact cause of any problem, but you'll be given as thorough a diagnosis as possible, and your chances of having another child with the same disorder outlined.
Can you benefit?
- if you've had a child with a genetic disorder such as cystic fibrosis, or a chromosomal disorder such as Down's syndrome
- if you've had a child with a congenital defect - for example, a club foot
- if there's any history of learning difficulties or abnormal development in your family
- if there's a blood relationship between you and your partner
- if you have a history of repeated miscarriages (see Incompetent cervix).
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