ABSTRACT
Although numerous studies have been published regarding concordance of anatomic features in MZ pairs, to our knowledge none has adequately controlled for the mirror phenomenon. In addition, no specific diagnostic test to establish the presence of mirroring has been previously published. Therefore, the frequency of mirroring has not been established for MZ twins. To address this practical deficit, this chapter describes the basic tools and a methodology to establish definitively the presence or absence of the mirror phenomenon.
