Prenatal Diagnosis of 49, XXXXY Syndrome: A Case Report With Literature Review

ABSTRACT Pentasomy 49,XXXXY is a rare sex chromosomal abnormality characterized by three extra X chromosomes in a male fetus. This condition is not related to maternal age, and phenotypic representations are non‐specific. Prenatal diagnosis of this condition is challenging with very few antenatally diagnosed cases. This case report discusses the prenatal diagnosis of 49,XXXXY using thickened nuchal fold as a pointer in the second trimester of a first‐trimester low‐risk pregnancy. Amniocentesis with fluorescence in situ hybridization (FISH) and karyotyping confirmed the diagnosis. This case highlights the significance of prenatal markers and their utility as a broader tool for other chromosomal anomalies beyond Trisomy 21, including sex chromosomal anomalies and the importance of a targeted anatomical survey for other signs of such anomalies. This approach would aid in patient counseling, genetic testing, and early decision‐making.