For many years it has been widely known that a ‘recessive’ condition, called Tay Sachs disease, is ten times more common in the Ashkenazi Jewish (AJ) population than in the wider population. Genetic screening for Tay Sachs carriers has been commonplace in the UK since it was first introduced in the 1980s. In the intervening years research has discovered several other recessive genes that are more common in the AJ population. Around the world, including in the UK, these findings led to the development of a panel test for common recessive genes, specific to the AJ population. For nearly 20 years, while working in the NHS, I was involved in the Tay Sachs screening programme, and the subsequent development of the extended panel of nine disorders.
You might remember the term ‘recessive’ if you did Biology GCSE. These are faulty genes we carry unknowingly. As all our genes come in pairs, having a recessive ‘mutation’ (like a spelling mistake in the gene code) in one half of the pair will not cause a person any health problems, so they are considered a healthy carrier. Of our 20,000 genes (each of which is an instruction telling the body how to work) we all carry half a dozen or so recessive mutations. So being a carrier of several genetic conditions is actually the normal human state, and nothing to worry about. The most important thing is to harness our understanding of genetics for good, so that people have the option to be screened for these conditions in order to help manage risk. I will come on to how we can manage these risks shortly, but first for a few other things to flag up.
The only time that being a carrier of a recessive gene matters, is if both members of a couple are carriers of the same gene. In this situation there is a 25% risk of having an affected child, if both parents pass on the faulty gene to the child.
Targeted panel tests are very useful for those with definite Ashkenazi lineage as they detect the high risk genes. This is currently offered in the UK by a community charity, Jnetics, via a clinic at Barnet Hospital.