It is different from choristoma, a closely related form of heterotopia. This gene is a candidate gene for periventricular heterotopia. Women with DCX mutations tend to have an anteriorly-predominant subcortical band heterotopia and pachygyria. While nasal glial heterotopia (NGH) is the preferred term, synonyms have included nasal glioma. Delany takes the term "heterotopia" from the writings of philosopher Michel Foucault. Grey matter heterotopia is such an example. This is by far the most common location for heterotopia. Subependymal heterotopia present in a wide array of variations. Choristomas, a form of heterotopia, are masses of normal tissues found in abnormal locations. Foucault outlines the notion of heterotopia on three occasions between 1966-67. A grey matter heterotopia is characterized as a type of focal cortical dysplasia. Far from the modernist heterotopia, the post modernist historicism contemporary hazards and the current tautologies. Band heterotopia may be complete, surrounded by simple white matter, or partial. Subcortical band heterotopia is caused by mutations in the microtubule-associated DCX gene. Gray matter heterotopia are common malformations of cortical development classed as neuronal migration disorders.