Endocrine Abstracts

Introduction: Hypoparathyroidism may be an isolated or a component of a complex syndrome. Although genetic disorders are not the most common cause, molecular analyses have identified a growing number of genes that when defective result in impaired formation of the parathyroid glands, disordered synthesis or secretion of parathyroid hormone.

Case presentation: We are reporting a 37-year-old gentleman, who is the first adult case diagnosed at our University Teaching Hospital. He was initially seen in the Genetics Clinic after his son was referred for assessment of congenital hearing loss, identified on new-born screening. Family history revealed the baby’s paternal family had several individuals with hearing loss and renal anomalies. Subsequent testing revealed that both patient and his son had a heterozygous likely pathogenic alteration for the GATA3 gene (c.815_816delinsTA p.Thr272Ile) consistent with a diagnosis of Hypoparathyroidism, Deafness and Renal Dysplasia (HDR) syndrome. Biochemistry confirmed asymptomatic hypoparathyroidism in our case and he was commenced on calcium supplementation.

Discussion: HDR syndrome, also known Barakat Syndrome is a rare genetic syndrome characterized by hypoparathyroidism, sensorineural deafness, and renal disease. Hypoparathyroidism leads to symptoms such as muscle pain, muscle spasms, seizures, and rarely, cardiomyopathy. Hearing loss is the most consistent feature of HDR syndrome. It is usually bilateral and can range from moderate to profound. The renal involvement includes structural renal anomalies and reflux however penetrance is reduced. HDR is inherited as an autosomal dominant disorder and is associated with genetic alterations involving the GATA3 gene, a zinc-finger transcription factor.

Conclusion: Taking a thorough clinical and family history is important when assessing patients to identify possible genetic clinical syndromes. The combination of hearing loss and hypoparathyroidism should prompt assessment for HDR syndrome, with cascade testing of family members following on and general genetic screening should be considered in young patients with sporadic hypoparathyroidism.