Summary
The HDR syndrome is an inherited condition consisting of hypoparathyroidism, sensorineural deafness and renal disease. The exact prevalence is unknown, but the disease is considered to be very rare, with about two dozen patients reported so far. Patients may present at any age with hypocalcemia, tetany, or afebrile convulsions. Hearing loss is usually bilateral and may range from mild to profound impairment. Renal disease manifestations include nephrotic syndrome, cystic kidney, renal dysplasia, hypoplasia or aplasia, pelvicalyceal deformity, vesicoureteral reflux, chronic renal failure, hematuria, proteinuria and renal scarring. The defect in the majority of cases was mapped to chromosome 10p (10pter-p13 region or 10p14-p15.1). Haploinsufficiency (deletions) of zinc-finger transcription factor GATA3, or mutations in the GATA3 gene appear to be the underlying cause of this syndrome. Inheritance is probably autosomal dominant, though autosomal recessive or X-linked inheritance were suspected in the original report. Diagnosis is based on the clinical findings and may be assisted by measurement of parathormone levels, an audiogram or auditory brain stem response study, renal imaging studies, and a renal biopsy. DNA analysis may demonstrate the presence of a submicroscopic deletion on chromosome 10p. Differential diagnoses include familial idiopathic hypoparathyroidism, progressive sensorineural deafness without renal disease, autosomal recessive hypoparathyroidism with renal insufficiency and developmental delay, and deletion 22q11 syndrome (see these terms). Management is multidisciplinary and consists of treating the clinical abnormalities associated with hypoparathyroidism, deafness and renal disease at the time of diagnosis. Prognosis depends on the nature and severity of the renal disease. *Author: Dr A. J. Barakat (September 2008)*.
