termsTerm
Deletion
aka deletions, deleted, gene deletion, homozygous deletion, copy number loss, copy-number loss, exon 19 deletion, exon 19 deletions
When a piece of DNA is missing, from a few letters to an entire gene. Deleting a tumour suppressor gene removes one of the cell's brakes.
Small deletions within a gene can either disable the protein (a frameshift that garbles the rest of the recipe) or, more rarely, activate it, as with the EGFR exon 19 deletions that make lung cancers sensitive to osimertinib. Large deletions remove whole genes, and losing both copies of a tumour suppressor such as PTEN, CDKN2A or RB1 is a frequent driver event. Some deletions create drug vulnerabilities: tumours that have lost MTAP become dependent on the enzyme PRMT5, an example of synthetic lethality.
Category
Biology basics