Thursday, 11 November 2010

MRCP revision battle 46.2: Tumour supressor genes and Li Fraumeni Syndrome

Tumour supressor genes code for proteins that provide a 'stop' signal to prevent cell division.  They therefore act as a barrier to the development of cancer.  As they are recessive genes both copies of the gene would have to be mutated to stop functioning.

The most famous tumour supressor gene is p53.

p53 is:
  • found on chromosome 17
  • the most commonly mutated gene in breast, colon and lung cancer
  • a key regulator of apoptosis and prevents entry into the S phase of the cell cycle until the DNA is checked.

Li Fraumeni Syndrome is a rare condition in which there is an autosomal dominant p53 mutation.  More rarely it may be caused by a CHEK-2 mutation. Li Fraumeni syndrome is characterised by early onset of cancer, especially breast, sarcoma or soft tissue.  

Lets move on to mitochondrial disorders...