HDR Syndrome

At a glance

HDR is an acronym that stands for Hypoparathyroidism, Deafness, and Renal dysplasia. It is defined by the triad of hypoparathyroidism, renal dysplasia, and hearing loss. The presence of Hirschsprung disease is reported. This association suggests a DiGeorge-like Syndrome characterized by hypoparathyroidism, heart defects, immune deficiency, deafness, and renal malformations caused by a haploinsufficiency of the zinc-finger transcription factor GATA3.

Synonyms

Baraka Syndrome; Nephrosis Nerve Deafness Hypoparathyroidism Syndrome.

History

A medical condition that was first described by Barakat et al in 1977. Amin J. Barakat (born November 2, 1942) is a Lebanese-American physician and presently a clinical professor of pediatrics and pediatric nephrology at Georgetown University.

Incidence

Approximately 40 cases described in the literature worldwide.

Genetic inheritance

Autosomal dominant disorder caused by mutations in the GATA3 gene on chromosome 10. Gene map location is 10p15. Rarer chromosomal anomalies are reported in combination with Hirschsprung disease like DiGeorge Syndrome, mosaic trisomy 8, XXY chromosomal constitution, partial duplication of chromosome 2q, tetrasomy 9p, and 20p deletion.

Pathophysiology

The GATA3 gene is part of the family of zinc-finger transcription factors; it is involved in vertebrate embryonic development and in the development of the parathyroids, inner ear, and kidneys.

Diagnosis

Diagnosis is based on clinical and laboratory stigmata, genetic testing, and family history.

Clinical aspects

The typical triad of HDR—sensorineural deafness, hypocalcemia and/or hypoparathyroidism, and nephropathy—is present in almost all patients. The manifesta­tion of renal involvement is variable and may range from vesicoureteral reflux to kidney aplasia. Developmental delay, seizure disorder, and a high incidence of cerebral infarcts have been described. Mild dysmorphic features may be present and may include hypertelorism, flat nose, proptosis, high-arched palate, micrognathia, and limb anomalies.

Precautions before anesthesia

Clinical examination with emphasis on facial malformations and routine blood work, including complete blood count, electrolytes, calcium, glucose, and kidney function test are required. Hematologic or biochemical disturbances, especially hypocalcemia, must be corrected prior to anesthesia. A complete medical history and current medication, for example, antiseizure drugs with the potential for drug interactions with anesthetic agents, must be documented. Anxiolysis is particularly important with deafness and mental retardation.

Anesthetic considerations

Calcium levels should be monitored regularly during blood transfusions or albumin infusions and corrected if necessary. Tracheal extubation can be difficult in patients with severe mental retardation because of the presence of chronic lung disease from recurrent aspirations and reduced ability to cough. In these more severely affected patients, the potential for postoperative mechanical ventilation must be considered and intensive care admission planned ahead.