Brain malformations in diprosopia observed in clinical cases, museum specimens and artistic representations

Abstract

Background Diprosopus is a rare malformation of still unclear aetiology. It describes a laterally double faced monocephalic and single-trunk individual and has to be distinguished from the variant Janus type diprosopus. Results We examined seven double-faced foetuses, five showing true diprosopus, and one each presenting as monocephalic Janiceps and parasitic conjoined twins. Four of the foetuses presented with (cranio)rachischisis, and two had secondary hydrocephaly. Three foetuses showed cerebral duplication with concordant holoprosencephaly, Dandy-Walker cyst and/or intracranial anterior encephalocele. In the Janiceps twins, cerebral duplication was accompanied by cerebral di-symmetry. In the parasitic twins the cyclopic facial aspects were suggestive of concordant holoprosencephaly. In one of the true diprosopus cases, pregnancy was achieved after intracytoplasmic sperm injection. Whole-exome sequencing, perfomed in one case, did not reveal any possible causative variants.The comparison of our double-faced foetuses to corresponding artistic representations from the Tlatilco culture allowed retrospective assignment of hairstyles to brain malformations. Conclusion Brain malformations in patients with diprosopus may not be regarded as an independent event but rather as a sequel closely related to the duplication of the notochord and neural plate and as a consequence of the cerebral and associated craniospinal structural instabilities.

Phenotypically Discordant Anomalies in Conjoined Twins: Quirks of Nature Governed by Molecular Pathways?

“…Laterally united conjoined twins share vast parts of their body (abdomen, thorax, neck, face and/or head) and classically consists of two phenotypes: parapagus dicephalus (two heads) and parapagus diprosopus (two laterally oriented faces in a single compound head). One of the more striking and relatively often occurring discordances found in dicephalic twins is anencephaly, with at least seven described cases appearing in the recent literature [9,14,15,[25][26][27][28]56]. These unilaterally occurring neural tube defects should be distinguished from concordant neural tube defects in parapagus diprosopus, which are the consequence of interaction aplasia, a phenomenon comprehensively described elsewhere [3].…”

Diprosopus: A Rare Case of Craniofacial Duplication and a Systematic Review of the Literature

“…Various authors suggested that duplication of the pituitary gland could be the least severe form of this anomaly [ 3 , 4 ]. Craniofacial duplication can happen together with a broad variety of anomalies, in particular those affecting the central nervous system, among which anencephaly is the most severe malformation described in diprosopus [ 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 ].…”

“…Craniofacial duplication can happen together with a broad variety of anomalies, in particular those affecting the central nervous system, among which anencephaly is the most severe malformation described in diprosopus [5][6][7][8][9][10][11][12][13][14][15].…”