Lyonization (X-chromosome inactivation)
Lionización (inactivación del cromosoma X)
- Date
- 1961 · confidence high
- Place
- Medical Research Council, Harwell, Oxfordshire, United Kingdom
- Credited to
- Mary F. Lyon
- Field
- Life & health
What was discovered
Lyon proposed that in female mammals one of the two X chromosomes is randomly inactivated in each cell during early embryonic development, thereby compensating gene dosage against males, who have only one X.
Susumu Ohno had observed in 1959 that one X chromosome appeared condensed, a direct clue that Lyon interpreted and formalised in her 1961 hypothesis.
What it led to
- Explanation of coat-colour mosaicism in heterozygous females (tortoiseshell mice)
- Clinical understanding of X-linked disease in carrier women
- Study of chromatin and Xist RNA in inactivation