Table 1.

Most frequently altered genes in BTCs

Gene	Type of alteration	Frequency	References
IDH	Mutation	6–36%	[13]
FGFR	Fusion	8–14%	[13–15]
TP53	Substitution/indel	27–59%	[13, 14]
ARID1A	Mutation	7–36%	[13]
KRAS	Substitution/indel	12–42%	[13, 14]
SMAD4	Mutation	21–30%	[13]
CDKN2A	Deletion	19%	[13]

CDKN2A: cyclin dependent kinase inhibitor 2A; indel: insertion-deletion mutation