Home            Q.009 Tumour suppressor genes

Which of the following is the least typical type of pathogenic gene alteration affecting a tumour suppressor gene?

A. deletion of a single nucleotide from within an exon
B. insertion of a single nucleotide within an exon
C. gene amplification
D. nucleotide substitution resulting in a premature stop codon
E. promoter methylation

C. gene amplification (increasing the number of gene copies in the genome) would normally cause an increased abundance of the protein product and increased activity rather than inactivation. This type of alteration is observed for some proto-oncogenes (eg MYCN). Insertion or deletion of a single nucleotide would cause a frameshift. Promoter methylation is associated with transcriptional inactivation.

See chapter 13 of the book for more information.