We discuss some effects associated to thin defects in extra dimensions. After describing the generation of quantum corrections localized at orbifold fixed points, we show some phenomenological implications of the localized terms and point out to generic problems of field theories in the presence of infinitely thin defects, which signal a breakdown of the low-energy expansion. We discuss possible physical interpretations and ways out of these phenomena. Finally, we examine some of these issues in a deconstructed orbifold, which can be regarded as an ultraviolet completion of these models.

PACS numbers: 11.10.Kk, 11.25.Mj, 12.15.Ff, 14.65.Ha