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

• Published in: Orphanet journal of rare diseases Vol. 18; no. 1; p. 57
• Main Authors: Rehder, Helga, Kircher, Susanne G, Schoner, Katharina, Smogavec, Mateja, Behunova, Jana, Ihm, Ulrike, Plassmann, Margit, Hofer, Manuel, Ringl, Helmut, Laccone, Franco
• Format: Journal Article
• Language: English
• Published: England BioMed Central Ltd 16-03-2023; BioMed Central; BMC
• Subjects: Anencephaly; Bones; Brain; Cerebral di-symmetry; CNS malformations; Conjoined twins; Diprosopus; Embryonic development; Encephalocele; Female; Health aspects; Holoprosencephaly; Holoprosencephaly - genetics; Humans; Janiceps; Male; Medical research; Museums; Neural plate; Nose; Notochord; Parasitic twin; Physiological aspects; Pregnancy; Prevention; Rare diseases; Retrospective Studies; Risk factors; Semen; Spinal cord; Twins; Twins, Conjoined; Germany; Cerebral di-symmetry; ICSI; Paul Klee; Parasitic twin; Tlatilco culture; Janiceps; Diprosopus; CNS malformations; Schedels world chronicle; Holoprosencephaly
• ISSN: 1750-1172; 1750-1172
• DOI: 10.1186/s13023-023-02617-5

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.
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.
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.