Before revision: Synthetic lethality arises when a combination of deficiencies in the expression of two or more genes leads to cell death , whereas a deficiency in only one of these genes does not.
After revision: or abolition of the expression of(whether by means of apoptosis or otherwise)the expression of or an abolition of the expression ofSynthetic lethality arises when a combination of deficiencies in the expression of two or more genes leads to cell death , whereas a deficiency in only one of these genes does not.