Children inherit many characteristics from their parents, such as the color of their eyes and hair color, and their height and build. Sometimes, a child can inherit a health condition. This happens when a
gene changes (mutates) and is passed down through a family. Each generation of children can inherit the
gene that causes the condition. A baby can inherit defective
genes from one or both of its parents.
Most inherited conditions are quite rare, affecting one person in every several thousands or millions of people.
There are more than 6,000 known single-
gene inherited conditions. Single
gene means that the condition is caused by changes (mutations) that occur in the DNA of one
Some conditions can be inherited from just one parent, such as Huntington's
disease and Marfan syndrome. Most inherited conditions cannot occur unless both the mother and father pass on the defective
gene; these include cystic fibrosis, sickle cell anemia, spinal muscular atrophy and Tay-Sachs
Inherited conditions can happen unexpectedly. Both parents can be healthy and unknowingly carry a defective
gene, which can be passed on to their baby, meaning the baby can be born with the inherited condition.
There are some
genetic conditions, such as Down's syndrome, that are usually not inherited. These generally result from a change in cells (mutation) when the cells divide in the earliest stages of pregnancy.
If you know that an inherited condition runs in your family, it's a good idea to seek advice before you try for a baby. Your doctor can offer advice about the risks of you passing on the condition. Depending on the type of condition, your doctor may recommend that you see a specialist for further testing or help, such as
genetic testing or
If you're already pregnant, your doctor can give you advice about prenatal screening, for example, where there is a strong family history of conditions such as muscular dystrophy, spina bifida or
Your doctor may ask you for a complete family medical history. If you don't already know, you will need to find out as much information as you can. For each family member, write down:
- their sex,
- their date of birth,
- their ethnic
- the dates of any medical problems,
- the diagnosis, and
- if appropriate, the cause and date of their death.
Ideally, the information you give your doctor should cover your brothers and sisters (if you have any), your parents, uncles, aunts and cousins. You doctor may also ask you about:
- any miscarriages,
- children in your family who have died, and
- half-brothers and sisters.
If a hereditary condition runs in your partner's family, you will need to find out this information about his family too.