HDR syndrome is characterized by hypoparathyroidism, sensorineural deafness, and renal issues. This condition is inherited and results from changes in the GATA3 gene located on chromosome 10p. It leads to hypoparathyroidism, which causes low calcium levels in the blood, resulting in persistent fatigue and depression. The deafness associated with HDR syndrome is congenital, and the kidney malformations can cause progressive renal failure. Some individuals may also have a small chin (micrognathia) and lack teeth. The syndrome is due to haploinsufficiency caused by alterations in the GATA3 gene, which render it inactive either physically or functionally. These alterations include deletions, some of which are large enough to be seen under a microscope, and point mutations in a single nucleotide base of the gene. The GATA3 gene is essential for the embryonic development of the ears, parathyroid glands, and kidneys. Accurate diagnosis of this syndrome can significantly impact a patient's life, as simple treatments can sometimes resolve complex issues. Supplemental calcium and calcidiol can help increase calcium levels, alleviate fatigue and depression, and greatly improve the patient's quality of life.