Most children are born healthy and well. However a few percent of children are born with a genetic disorder, disability or birth defect (congenital anomaly).

We all carry changes in our genes that predispose our children to developing a genetic disorder. It is a matter of chance as to whether a partner carries a fault in the same gene or not. For most couples, there is no indication that they are at increased risk. 

In some disorders, inheriting a single gene fault or a combination of faulty genes is sufficient to cause disease. In others, the genetic susceptibility requires additional genetic and/or environmental factors to lead to disease.

The consequences depend on which particular one of our approximately 25,000 genes is affected.

Preconception genetic screening is now routine practice.

Who should be assessed?

Understanding who is at risk and what the potential risks are is pivotal in advising on pre-conceptional screening. Important clues can be present in our medical history, our family history, our ethnic (genetic) background, or unearthed through screening tests carried out before starting a family.

Ethnicity: a major clue to our genetic inheritance.

Our ethnicity provides a clue as to what genetic changes we are likely to carry. Typically these genetic changes are in "recessive genetic conditions" that only manifest in a child where both partners carry a change in the same gene.

To be affected, a child needs to inherit a double dose of the faulty gene - one from each parent. Common examples of autosomal recessive disorders are the blood disorder thalassaemia, which occurs in Southern European, Mediterranean and Asian populations, where up to 1 in 10 individuals may be a carrier; and cystic fibrosis , the most common recessive genetic disorder in the north-west European population, where 1 in 25 is a carrier.

In practice, there are only a few ethnic based screening programs in existence. Preconception screening utilises ethnicity to target readily detectable, common disorders and common mutations (gene faults). This screening can show the probability of developing a disorder but is not a comprehensive evaluation. 

Current guidelines recommend screening. It increasingly possible to do this in one simple test. Primary Care Genetics is a specialist private practice with pre-eminent expertise in preconceptional (pre-family) genetic testing.