HDR syndrome: The syndrome of familial Hypoparathyroidism, sensorineural Deafness, and Renal dysplasia. Inherited as an autosomal dominant trait, the syndrome is caused by haploinsufficiency of the GATA3 gene in chromosome 10p.
The hypoparathyroidism causes hypocalcemia (a low level of calcium in blood) and lifelong fatigue and depression. The deafness is congenital (present at birth). The kidney dysplasia (malformations) can lead to nephrosis and progressive renal failure. Some patients have micrognathia (small chin) and no teeth.
Haploinsufficiency is caused by changes in the GATA3 gene that render it physically or functionally inactive. These changes include deletions, some of them large enough to be detected under the microscope, and point mutations of a single nucleotide base in GATA3.
The GATA3 gene appears essential to the embryonic development of the ears, parathyroid glands, and kidneys.
Diagnosis of this syndrome (as with many diseases) can make a great difference in a patient's life. (Sometimes seemingly difficult diagnoses need simple treatments.) Supplemental calcium and calcidiol (vitamin D) can increase the calcium, relieve the fatigue and depression (and transform the quality of life) for the patient.