Unusual Neonatal Presentation of 48,XXYY - Report - MDSpire

Unusual Neonatal Presentation of 48,XXYY

  • By

  • Jess Allerton

  • February 10, 2026

  • 3 min

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Clinical Report: Unusual Neonatal Presentation of 48,XXYY

Overview

This case report details a rare neonatal presentation of 48,XXYY syndrome characterized by ambiguous genitalia and Tetralogy of Fallot, emphasizing the critical role of early genetic testing in improving outcomes for newborns with these conditions.

Background

48,XXYY syndrome is a rare sex chromosome aneuploidy with an estimated prevalence of 1 in 18,000 to 1 in 50,000 live male births. It is recognized as a distinct condition with a broader clinical profile than previously thought, including developmental and endocrine issues that require early intervention.

Data Highlights

No numerical data available in the article.

Key Findings

The infant presented with ambiguous genitalia, including bilateral inguinal testes and a micropenis. Tetralogy of Fallot was diagnosed, which is an uncommon cardiac defect in 48,XXYY syndrome. Normal gonadotropin and adrenal hormone levels were observed for the infant's age. Pelvic ultrasonography confirmed the presence of bilateral testes without Müllerian structures. This case expands the known clinical spectrum of 48,XXYY syndrome. Early genetic and cardiac evaluations are essential for newborns with ambiguous genitalia.

Clinical Implications

Healthcare providers should maintain a low threshold for genetic evaluation in newborns with ambiguous genitalia or congenital heart defects. Multidisciplinary management involving pediatric endocrinology, cardiology, urology, and genetics is recommended for optimal care, with each specialty addressing specific aspects of the patient's needs.

Conclusion

This case highlights the rare combination of ambiguous genitalia and Tetralogy of Fallot in a neonate with 48,XXYY syndrome, emphasizing the importance of early genetic assessment and interdisciplinary care, and its implications for future cases.

References

  1. Gazzaz N., Clinical Case Reports, 2026 -- A Rare Neonatal Case of 48,XXYY Syndrome Presenting With Ambiguous Genitalia and Tetralogy of Fallot
  2. Frontiers in Endocrinology — Rare SRY-negative 46,XX disorder of sex development with male phenotype and ectopic gonads: a case report
  3. The Journal of Clinical Endocrinology & Metabolism — Genetic and Clinical Characteristics of 185 Japanese Children With 46,XY Differences of Sex Development
  4. The Journal of Clinical Endocrinology & Metabolism — Management Strategies for Patients Diagnosed with Turner Syndrome
  5. Endocrine Reviews — New Horizons in Klinefelter Syndrome: Current Evidence, Gaps, and Research Priorities
  6. Rare SRY-negative 46,XX disorder of sex development with male phenotype and ectopic gonads: a case report
  7. Genetic and Clinical Characteristics of 185 Japanese Children With 46,XY Differences of Sex Development
  8. Management Strategies for Patients Diagnosed with Turner Syndrome
  9. New Horizons in Klinefelter Syndrome: Current Evidence, Gaps, and Research Priorities
  10. AMBIGUOUS GENITALIA IN THE NEWBORN
  11. Received: 14 February 2020
  12. Yield of Whole Genome Sequencing for Pathogenic Single Nucleotide Variants in Congenital Heart Disease: A Systematic Review and Meta-Analysis - PubMed

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