DiGeorge Syndrome (DGS), or 22q11.2 deletion syndrome, is a multisystem congenital disorder typically diagnosed in infancy due to its classic triad of cardiac defects, palatal abnormalities, and hypocalcemia from hypoparathyroidism. Diagnosis in adulthood is rare and presents a significant clinical challenge. We aim to report an exceptional case of DGS that remained undiagnosed for 31 years, to highlight the profound impact of information fragmentation in healthcare and emphasize the critical importance of a comprehensive pediatric history in solving complex adult-onset presentations.

We present the case of a 31-year-old woman who presented with seizures. A comprehensive retrospective review of all available medical records, including detailed neonatal hospitalization data from 1993, was conducted. The current diagnostic workup included clinical evaluation, serial biochemical analyses, and structural imaging. The definitive diagnosis was pursued through Whole Exome Sequencing (WES) for copy number variation analysis, followed by targeted Multiplex Ligation-dependent Probe Amplification (MLPA) for confirmation.

The 31-year-old female presented with a generalized seizure. The workup revealed the biochemical hallmarks of hypoparathyroidism: severe hypocalcemia (ionized Ca 0.71 mmol/L), hyperphosphatemia (5.9 mg/dL), and an inappropriately low PTH (12.9 pg/mL). A retrospective review uncovered a strikingly similar neonatal course in 1993, including hospitalizations for seizures with severe hypocalcemia. The history of the patient was also positive for a 0.68 cm type 2 ventricular septal defect (VSD) at birth and a cleft palate which was repaired at age 13. Physical exam revealed dysmorphic facies. While WES was negative for pathogenic single-nucleotide variants, it identified a large deletion on chromosome 22q11.2, which was definitively confirmed by MLPA as a 22q11.2 deletion spanning the LCR22-A to LCR22-C regions.

This case represents a profound, 31-year diagnostic odyssey of DiGeorge Syndrome, despite a well-documented presentation in the neonatal period. The diagnostic delay was primarily caused by information fragmentation and the resolution of key clinical clues such as the VSD and cleft palate. This powerfully illustrates that clinicians must maintain a high index of suspicion and perform a meticulous review of pediatric records when faced with unexplained conditions like adult-onset hypoparathyroidism. Even decades later, establishing a correct diagnosis is critical for long-term management, genetic counseling, and highlights the urgent need for improved transitional care for patients with complex congenital disorders.