ESPE Abstracts

Background: Hypoparathyroidism, sensorineural deafness, and renal disease (HDR syndrome, Barakat syndrome) is a rare condition, caused by a mutation on chromosome 10p which affects the GATA3 gene. GATA3 encodes a transcription factor important for the embryonic development of the parathyroid gland, the auditory stem, and the kidneys. Its expression has also been found in the thymus and the central nervous system. A wide range of renal involvement has been reported in the literature – agenesis, hypoplasia, cystic kidneys, vesicoureteral reflux, nephritic syndrome, hematuria, chronic kidney disease and renal failure.

Clinical case: A 14-year old boy was admitted to Endocrinology department with history of a bilateral sensorineural hearing loss, tic disorder at the age of 11 years, 2 generalized epileptic seizures in the last month, calcification in the basal ganglia imaged on cranial CT. Chovestek’s sign was positive. Biochemical tests revealed hypocalcemia: total Ca 5.01 mg/dl (8.6–10.2), ionized Ca 2.60 mg/dl (4.8–5.5), hyperphosphatemia: 10.04 mg/dl (2.7–4.5), parathyroid levels not consistent with hypocalcemia: 20 pg/ml (15–65), levels of ACTH, cortisol rhythm, TSH and fT4 in the reference range. Liver and renal function were normal. Urinalysis did not show proteinuria and hematuria. Urine volume in 24 hours was 1500 mL with normal urine calcium, phosphorus, and creatinine levels. No chromosomal abnormalities were detected on standard G-banding analysis. Ultrasound of the kidneys revealed absence of the right kidney with a compensatory hypertrophy of the left one. Renal agenesis was subsequently diagnosed by DMSA scintigraphy. Echocardiogram showed normal heart function. Initial treatment was with parenteral calcium gluconate infusion followed by peroral calcitriol and calcium supplementation. The patient was receiving valproic acid for symptomatic epilepsy. He was discharged with peroral dihydrotachysterol and a high-calcium, low-phosphorous diet.

Conclusion: HDR syndrome is a genetic disorder with phenotypic variability. Diagnosis is based on the clinical finding. In conclusion, we recommend that, a patient presenting with seizures associated with deafness, should undergo determination of serum calcium, phosphate and parathyroid hormone, as well as renal imaging.