Abstract 3: Picking up DiGeorge syndrome in Hypoparathyroidism: A hit-and-miss “thumbing” diagnosis

Background: Hypoparathyroidism is commonly idiopathic (besides post-surgical). Syndromic forms are mostly sporadic and it is the specific clinical features which help to identify the relevant diagnosis. Many times, these syndromic features are subtle and may be missed in a busy clinical practice. Also, the Ca-P deposition in the brain may lead to overlapping neurological features. Conversely hypoparathyroidism (17 – 60%) may not be part of the initial clinical presentation in these syndromes. Case Report: We report a 26-year male who presented with seizure disorder and hypocalcemia, poorly controlled on anti-epileptics and oral calcium. Apart from seizures, which commenced at the age of 12 days, he had a history of recurrent chest infections and middle ear infections requiring multiple hospitalizations (8 – 10 till date). The patient had a reduced attention span, irritable behaviour, and poor scholastic performance. On examination, the patient had low set ears, carious teeth, high pitched nasal voice, positive Trousseau's sign, mucopurulent discharge with perforation of the tympanic membrane in both ears. Investigations revealed hypocalcemia (6.3 mg/dl) with hyperphosphatemia (6.4 mg/dl) with inappropriately low iPTH (11.4 pg/ml) levels. Non-contrast CT head showed bilateral calcification at the basal ganglia and thalamus. 2 D echocardiography did not reveal any cardiac abnormality. CT thorax revealed absence of thymus. A deformity was noted at the distal phalynx of both thumbs, which on X-rays was identified as a small bony outgrowth from the distal phalynx of bilateral thumbs. It was actually a preaxialpolydactyly type II (Wassel's classification). These two pointers led us to do specific genetic testing for DiGeorge syndrome and Next-generation sequencing (NGS) revealed microdeletion at chromosome 22q11.2. Conclusion: The spectrum of DiGeorge syndrome is vast and varied. The characteristic defects including congenital heart disease and velo-facial manifestations may not be present in all. Looking out for subtle clinical pointers to syndromic features may help in directing specific genetic testing to clinch the diagnosis. In our case, the deformed shape of the thumbs led us to explore further leading us to unravelling the diagnosis.