Sirenomelia: A multi-systemic polytopic field defect with ongoing controversies

Lucas L. Boer, Eva Morava, Willemijn M. Klein, Annelieke N. Schepens-Franke, Roelof Jan Oostra

Research output: Contribution to journalReview articlepeer-review

13 Scopus citations


The most impressive phenotypic appearance of sirenomelia is the presence of a 180°-rotated, axially positioned, single lower limb. Associated gastrointestinal and genitourinary anomalies are almost always present. This rare anomaly is still the subject of ongoing controversies concerning its nosology, pathogenesis, and possible genetic etiology. Sirenomelia can be part of a syndromic continuum, overlapping with other complex conditions including caudal dysgenesis and VATER/VACTERL/VACTERL-H associations, which could all be part of a heterogeneous spectrum, and originate from an early defect in blastogenesis. It is imaginable that different “primary field defects,” whether or not genetically based, induce a spectrum of caudal malformations. In the current study, we review the contemporary hypotheses and conceptual approaches regarding the etiology and pathogenesis of sirenomelia, especially in the context of concomitant conditions. To expand on the latter, we included the external and internal dysmorphology of one third trimester sirenomelic fetus from our anatomical museum collection, in which multiple concomitant but discordant anomalies were observed compared with classic sirenomelia, and was diagnosed as VACTERL-H association with sirenomelia.

Original languageEnglish (US)
Pages (from-to)791-804
Number of pages14
JournalBirth Defects Research
Issue number10
StatePublished - Jun 1 2017


  • Anatomical museum
  • Blastogenesis
  • Caudal dysgenesis
  • Mermaid syndrome
  • Sirenomelia
  • Teratology

ASJC Scopus subject areas

  • Pediatrics, Perinatology, and Child Health
  • Embryology
  • Toxicology
  • Developmental Biology
  • Health, Toxicology and Mutagenesis


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