Nephropathy-deafness-hyperparathyroidism syndrome

Nephropathy-deafness-hyperparathyroidism syndrome, also known as Barakat syndrome or HDR syndrome (Hypoparathyroidism, Deafness, and Renal dysplasia syndrome), is a rare genetic disorder characterized by the triad of hypoparathyroidism (not hyperparathyroidism as the older naming convention suggested), sensorineural hearing loss, and renal anomalies. The condition is caused by mutations or deletions in the GATA3 gene located on chromosome 10p, which encodes a transcription factor critical for the development of the parathyroid glands, inner ear, and kidneys. The disease affects multiple organ systems. Hypoparathyroidism leads to low calcium levels in the blood (hypocalcemia), which can cause muscle cramps, tingling, and seizures. Sensorineural deafness is typically bilateral and can range from mild to profound, often presenting in childhood. Renal abnormalities are variable and may include renal dysplasia, hypoplasia, aplasia, vesicoureteral reflux, or nephrotic syndrome, which can progress to chronic kidney disease or renal failure in some cases. Not all patients manifest all three features of the classic triad, and clinical expression can be highly variable even within the same family. Treatment is supportive and symptom-directed. Hypoparathyroidism is managed with calcium and active vitamin D supplementation to maintain normal blood calcium levels. Hearing loss may be addressed with hearing aids or cochlear implants. Renal complications are managed according to the specific abnormality present, and patients with progressive kidney disease may ultimately require dialysis or kidney transplantation. Regular monitoring of renal function, calcium metabolism, and hearing is recommended. Genetic counseling is important for affected families.

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