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Synonym(s) -
Prevalence <1 / 1 000 000
Inheritance Not applicable
Age of onset Neonatal
  • Q87.2
  • C0037205
  • C538595
  • 10049216


Sirenomelia is a lethal congenital anomaly that is characterized by a single midline lower limb, sacral and pelvic bone anomalies, aberrant abdominal umbilical artery (persistent vitelline artery), absent external genitalia, imperforated anus, renal dysgenesis or agenesis and facial dysmorphism (Potter's facies; large, low-set ears, prominent epicanthic fold, hypertelorism, flat nose and receding chin). Sirenomelia may be considered as the severe end of a spectrum of caudal regression sequence (see this term). It shares some features with VACTERL/VATER association (see this term): vertebral anomaly, anorectal malformation, cardiac defect, tracheo-oesophageal fistula, renal and limb anomaly. Risk factors include maternal diabetes, teratogens, genetic factors and maternal age < 20 years.

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