The application relates to means, which derive from TAL effectors and TALENs. The structure of the means of the application is especially adapted for partial or full deletion of at least one DNA tandem repeat, more particularly for partial or full deletion of at least one DNA tandem repeat in a double-stranded DNA, more particularly for partial or full deletion of at least one DNA tandem repeat, which is contained in a double-stranded DNA and, which forms a complex secondary structure, such as a hairpin, a triple helix or a tetraplex secondary structure. The means of the application are notably useful in the treatment and/or prevention and/or palliation of a disease or disorder involving at least one DNA tandem repeat, such as DM1, SCA8, SCA12, HDL2, SBMA, HD, DRPLA, SCA1, SCA2, SCA3, SCA6, SCA7, SCA17, PSACH, DM2, SCA10, SPD1, OPMD, CCD, HPE5, HFG syndrome, BPES, EIRE1, FRAXA, FXTAS and FRAXE.
