Mary Lyon (1925–2014)

Colleagues in the School of Biological Sciences remember Professor Mary Lyon, one of the foremost geneticists of the 20th century.

Professor Lyon was a student at the University, graduating with a PhD in genetics in 1950, and then a member of staff here until 1954.

She went on to conduct research that had a fundamental impact on our understanding of mammalian genetics and human medical genetics.

Her greatest achievement was to propose the theory of X chromosome inactivation. This process, now known as Lyonisation, suggested that one of the two X chromosomes in the cells of female mammals is randomly inactivated during early development.

The theory greatly advanced the understanding of X-linked, inherited diseases, including Duchenne muscular dystrophy and haemophilia and remains relevant to contemporary research into how genes are regulated as we develop and grow.

Professor Lyon's interest in biology began when she won books on wild flowers, birds and trees in a school essay competition. She read zoology, physiology and biochemistry at Girton College, Cambridge, before beginning her PhD there.

She transferred her research to the University of Edinburgh to take advantage of the better facilities available and studied under the supervision of Douglas Falconer.

After completing her PhD, Professor Lyon was offered a position in Toby Carter’s research group, studying the genetic hazards of radiation.

She left the University in 1954, moving with the research group to the Medical Research Council Radiobiological Research Unit at Harwell where a new genetics division was being established.

Professor Lyon took over the division in 1962. It was there that her curiosity and fascination with the humble mouse and the extraordinary number of mouse genetic variants led to her many discoveries and transformed our understanding of mammalian genetics.

Professor Lyon retired in 1990 but continued her academic work until 2012. She was elected a Fellow of the Royal Society in 1973 and won numerous awards and honours during her career including the Royal Medal in 1984.

The MRC Harwell Mary Lyon Centre, a national facility for mouse functional genomics, opened in 2004 and last year the UK Genetics Society created the Mary Lyon Medal in her honour.