Abstract
BackgroundThe microdeletion of chromosome 22q11.2 is the most common human deletion syndrome. It typically presents early in life and is rarely considered in adult patients. As part of the manifestations of this condition, patients can have parathyroid glandular involvement ranging from hypocalcemic hypoparathyroidism to normocalcemia with normal parathryroid hormone levels. The first manifestation of the syndrome might be seizures due to profound hypocalcemia.Case presentationA 40-year-old man without significant past medical history presented with a new-onset generalized tonic-clonic seizure. He had no personal history of hypocalcemia or seizures. Physical examination was remarkable for short stature, hypertelorism, prominent forehead and nasal voice. His initial laboratory examination showed hypocalcemia (Calcium 5.2 mg/dl and Calcium ionized 0.69 mmol/l) with hypoparathyroidism (Parathyroid hormone intact < 2.5 pg/ml. NV: 14–72 pg/ml). Urine Calcium was 3 mg/dl on a spot and 88 mg in a 24-hour urine collection (NV: 100–300 mg/24 hs). The electrocardiogram showed a prolonged corrected QT interval. Echocardiogram, abdominal ultrasound and electroencephalogram were normal. A computer tomography of the brain showed basal ganglia calcification. The subtle physical findings and the presence of idiopathic hypoparathyroidism motivated the performance of fluorescent in situ hybridization which demonstrated a microdeletion on one of the homologs 22q11.2. The patient was treated with calcium citrate and calcitriol with good response.ConclusionMicrodeletion of chromosome 22q11.2 is among the most clinically variable syndromes, with more than 180 features associated with the deletion. It has a variable phenotypical expression, requiring a high level of awareness for its early diagnosis. Seizures, related to marked hypocalcemia due to idiopathic hypoparathyroidism, might be the presenting feature in an adult patient with this syndrome.
Highlights
The microdeletion of chromosome 22q11.2 is the most common human deletion syndrome
Less commonly a genetic disorder like chromosome 22q11.2 deletion syndrome can be the culprit condition. In this syndrome the parathyroid glandular dysfunction ranges from hypocalcemia with hypoparathyroidism to normocalcemia with normal parathryroid hormone levels [1,2,3]
There are only a few reports in the medical literature which describe new onset seizures caused by hypocalcemia in adolescence or adulthood, in patients not previously diagnosed with chromosome 22q11.2 deletion syndrome [1,3,7,9,10]
Summary
Chromosome 22q11.2 deletion syndrome has a variable phenotypic expression. This diagnosis should be considered in adult patients presenting with idiopathic hypoparathyroidism. The absence of the classical features of this condition should not exclude this pathology. Seizures, related to marked hypocalcemia, might be the initial presentation of this deletion. Treatment is relatively simple and can bring about profound clinical improvement
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