The study posted by OP discusses 3 different varieties of alteration:
DNA mutation (permanent change in the sequence of ACGT nucleotide bases)
Changes in gene expression (usually describes a transient/temporary change in the level of protein product of a gene, can be persistently influenced by DNA methylation)
DNA methylation (typically refers to conversion of Cytosine bases to methyl-Cytosine, which is heritable from mother cell to daughter cell, making it a persistent change)
Anyone making assertions regarding one of these topics should understand the basics of the linked content prior to posting.
Feel free to post contradictory evidence if I’m mistaken, but none of the drugs featured on this site are considered mutagenic.
As far as Isotretinoin/Accutane goes, it is considered to have anti-androgenic, anti-proliferative, and anti-inflammatory effects, on its own, and/or via isomerization to retinoic acid followed by interaction with retinoic acid receptors, which is in turn results in changes in gene expression. An important question that has been largely ignored is whether or not Accutane induces persistent changes in gene expression via DNA methylation, and what genes are affected in which tissues. Also, DNA methylation could explain its teratogenicity (ability to cause abnormalities in physical development).