Who Do You Think You Are?

We are all born with a set of genes – yet not all of them are operating at any one time. In fact they appear to switch on and off. What is the mechanism that controls them?

After the completion of the Human Genome Project – the mapping of the entire human DNA sequence - it was still not clear to scientists why certain genes were silent or active during the development of a human lifetime.

The answer to this question appears to involve microscopic controlling mechanisms called epigenetic marks, which Cambridge geneticist, Dr Wolf Reik will explore in ‘Who Do You Think You Are?”, a lecture on 19 March at Lady Mitchell Hall.

German-born Dr Wolf Reik is Head of the Laboratory of Developmental Genetics and Imprinting at Babraham Institute, Cambridge.

His team has carried out extensive research into epigenetic marks and imprinting of mammals. Dr Reik has won a number of honours and prizes including the 1994 Wellcome Prize in Physiology.

Scientists have revealed that as individuals reach various stages of their lives, different genes are switched on or off. This process plays a crucial role during our development, allowing proteins to be produced only when they are needed.

It is not clear why these genes would switch on or off, but it appears that epigenetic marks play an important role. Understanding just how they work could lead to a deeper understanding of diseases as we age.

Epigenetic marks are additions of certain types of molecules to our genes and chromosomes that affect the other ‘machinery' of the cell, telling the cell when each gene can be expressed.

In having children, we pass on copies of our genes – half from the mother, half from the father.

Special types of epigenetic marks, called epigenetic imprints, dictate which copy of the gene should be used – the mother's or the father's. In general, an imprint from a mother suppresses cell growth, while a copy from a father will stimulate growth.

Because epigenetic marks play such an important role during development, a defect in one of them can be as serious as a mutation in a gene.

Intriguingly, scientists believe that epigenetic marks also act as a memory centre of our ancestors' experiences. These marks can be altered during a stressful period in an individual's lifetime, such as a famine.

The result is that a starving mother will see problems not only in her children, such as lower than normal birth weight, but potentially in her grandchildren as well - and possibly even her great-grandchildren.

‘Who do you think you are?' lecture takes place at the Lady Mitchell Hall, Sidgwick Avenue on March 19 at 7.30pm. Entrance is free with no need to book. Street parking is available.