Makindo Medical Notes

Edwards Syndrome (Trisomy 18) 👶🧬: A severe chromosomal disorder caused by an extra copy of chromosome 18. It carries very high perinatal mortality, with <10% surviving beyond the first year.

About ℹ️

• Incidence: ~1 in 5,000 live births.
• Sporadic – usually not inherited, caused by random nondisjunction.
• Median survival: weeks to months; very few live beyond infancy.

Aetiology 🧪

• Chromosomal nondisjunction: Failure of chromosome 18 to separate correctly during meiosis.
• Advanced maternal age: Important risk factor.
• Mosaicism (~5%): Only some cells carry trisomy 18 → milder phenotype, occasionally longer survival.

Clinical Features 👩‍⚕️

• Cardiac: Congenital heart defects (e.g., VSD, PDA, polyvalvular disease).
• Face & Head: Microcephaly, prominent occiput, micrognathia, low-set ears.
• Hands: Characteristic clenched fists with overlapping fingers ✋.
• Growth: Intrauterine growth restriction (IUGR) → low birth weight, failure to thrive.
• Neurodevelopment: Severe intellectual disability, hypotonia → hypertonia with age.
• Other malformations: Horseshoe kidney, spina bifida, diaphragmatic hernia, omphalocele.

Differential Diagnoses 🧩

• Patau Syndrome (Trisomy 13): Holoprosencephaly, polydactyly, cleft lip/palate.
• Down Syndrome (Trisomy 21): Milder, associated with hypotonia, intellectual disability, distinctive facies.
• Other chromosomal anomalies (e.g., Turner, Cri-du-chat).

Investigations 🔬

• Karyotyping: Definitive diagnosis of Trisomy 18.
• Prenatal screening:
  • NIPT (cell-free fetal DNA).
  • CVS or amniocentesis for confirmation.
  • Ultrasound: growth restriction, congenital malformations (esp. cardiac).

Management ❤️

• Supportive care: Feeding support, oxygen, seizure control.
• Palliative approach: Often chosen, focusing on comfort and dignity.
• Multidisciplinary input: Neonatology, cardiology, neurology, physiotherapy, palliative care team.
• Genetic counselling: Essential for families; recurrence risk is low but higher with maternal age.

Prognosis 📈

• Median survival: days to weeks.
• ~10% survive beyond the first year; survivors have profound developmental delay and multiple medical needs.

References 📚

• Genetics Home Reference – Edwards Syndrome
• NHS – Edwards Syndrome

💡 Exam Pearl

"18 = clenched fists" ✋ Think Edwards: growth restriction, prominent occiput, micrognathia, congenital heart disease, overlapping fingers. Diagnosis = karyotype confirmation ✅.