TITLE:
Heterokaryotypic Monozygotic Monochorionic Twin Pregnancy: A Case Report of a Rare Occurrence
AUTHORS:
Janisha Silva Raju, Ravichandran Jeganathan
KEYWORDS:
Heterokaryotypia of Monozygotic Twins, Discordant Monochorionic Twins, Discordant Karyotypes, Cytogenetic Sampling, Selective Feticide
JOURNAL NAME:
Open Journal of Obstetrics and Gynecology,
Vol.15 No.12,
December
12,
2025
ABSTRACT: Heterokaryotype in monozygotic twinning is a rare phenomenon in which the number and appearance of chromosomes differ between the monozygotic pair. Although traditionally, monozygotic pair presumed to be identical, the loss or gain of an entire or part of a chromosome during the cell divisions shortly after fertilization may yield discordant karyotypes. We report a prenatal sonographic finding and the cytogenetic analysis of a monochorionic twin of a spontaneous conception, discordant for severe fetal anomaly. This case emphasizes the clinical relevance of dual cytogenetic sampling in cases of monochorionic twins with discordant sonographic anomalies. Structural abnormalities occur more common in monozygotics compared with dizygotics or singletons. Selective feticide is a treatment option and a favorable outcome of the normal co-twin may be achieved.