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Conjoined Twins

  • Reference work entry
Atlas of Genetic Diagnosis and Counseling

  • 275 Accesses

Conjoined twins are incompletely separated monozygotic twins. They have long fascinated both medical profession and lay public. Such events are rare and occur in 1/50,000 to 1/100,000 births and 1 in 400 sets of monozygotic twins. Over 60% succumb in utero or are stillborn (Spitz 2005). It is a complication of monochorionic twinning at 13–15 days after conception.

Synonyms and Related Disorders

Cephalopagus; Craniopagus; Dicephalus; Diprosopus; Epigastrius; Fetus-in-fetu; Ischiopagus; Omphalopagus; Pygoparus; Rachipagus; Thoracopagus

Genetics/Basic Defects

  1. 1.

    Conjoined twins

    1. a.

      Rare variants of monozygotic, monochorionic twins

    2. b.

      Two theories of conjoined twin formation

      1. i.

        Resulting from the secondary union of two originally separate monovular embryonic disks

      2. ii.

        Resulting from an incomplete separation of the inner cell mass at around 13–15 days of gestation of the monovular twins

    3. c.

      Twins can be conjoined at any site from the cranium downward to the sacrococcygeal region

      ...

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Editor information

Editors and Affiliations

  1. Perinatal and Clinical Genetics, Department of Pediatrics, LSU Health Sciences Center, 1501 Kings Highway, Shreveport, LA, 71130, USA

    Harold Chen

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© 2012 Springer Science+Business Media, LLC

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(2012). Conjoined Twins. In: Chen, H. (eds) Atlas of Genetic Diagnosis and Counseling. Springer, New York, NY. https://doi.org/10.1007/978-1-4614-1037-9_57

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