Left microtia in one monozygotic twin. A case report.

Area of Science:

• Reproductive Medicine
• Developmental Biology
• Medical Genetics

Background:

• Monoamniotic twins, sharing a single amniotic sac, represent a rare twin gestation with significant risks.
• These twins experience higher rates of congenital anomalies, predominantly structural defects, compared to dichorionic twins.
• While discordant phenotypes are documented, external ear malformations in this specific twin type remain exceptionally rare.

Observation:

• This report details a unique case of monoamniotic twins achieving double survival.
• One twin presented with a distinct congenital anomaly: left microtia, a malformation of the external ear.
• Additionally, this twin was diagnosed with a single umbilical artery, a condition often associated with other fetal abnormalities.

Findings:

• The case highlights a previously unreported discordant phenotype in surviving monoamniotic twins.
• The co-occurrence of microtia and a single umbilical artery in one twin provides new data on potential developmental pathways.
• This observation contributes to the understanding of the spectrum of congenital anomalies in monoamniotic twins.

Implications:

• This case underscores the importance of detailed fetal anomaly screening in all twin gestations, especially monoamniotic twins.
• Further research into the etiology of discordant phenotypes in monoamniotic twins is warranted.
• Understanding these rare presentations can improve diagnostic accuracy and management strategies for high-risk twin pregnancies.