Two Cases of Chromosome 22q11.2 Deletion Syndrome Diagnosed in 12-Year-Old Boys with Hypocalcemic Seizures
A 12-year-old boy presented with a new onset generalized tonic-clonic seizure. He is the second child of phenotypically normal parents, born at term after an uneventful pregnancy by an uncomplicated caesarean section with low birth weight of 2,800 g (10–25th percentile). At age 1 year, the child underwent surgical repair of patent ductus arteriosus. At age 6 and 7 years, he had two episodes of febrile convulsion. He had a learning difficulty in his school-aged years. He did not have any family history of similar clinical conditions.\nPhysical examination was abnormal due to a prominent forehead, small down-turned mouth, micrognathia and bifida uvula. His height was 155.8 cm (90–97th percentile) and weight was 59.7 kg (75–90th percentile). Chvostek’s and Trousseau’s signs were negative. On neurological evaluation, his verbal fluency was decreased.\nThe ECG showed a prolonged corrected QT interval and chest X-ray failed to show a thymus shadowing. The brain CT revealed calcification located in the left basal ganglia (). The EEG was abnormal due to generalized intermittent slow waves without any epileptiform discharges.\nLaboratory tests showed hypocalcemia (calcium 6.9 mg/dL, ionized calcium 3.8 mg/dL), hyperphosphatemia (8.3 mg/dL) and normal level of magnesium (1.7 mg/dL). PTH was normal with 21.91 pg/mL (reference range 15–65 pg/mL) and 25-vitamin D3 was decreased to 22.9 ng/mL (reference range 30–60 ng/mL). Peripheral blood count, hepatic and renal function tests were all within normal range except mild thrombocytopenia (130,000/μL). A 22q11.2 deletion was confirmed by a FISH analysis.\nThe patient was treated with calcium citrate and calcitriol. He remained asymptomatic with normal serum calcium level with medications.