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

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.