A rare genetic hypoparathyroidism characterized by severe hypocalcemia, seizures, hyperphosphatemia, and undetectable parathyroid hormone levels, in the absence of parathyroid tissue. Complications include psychomotor and growth delay, delayed dentition, and cataracts.

A rare, primary bone dysplasia characterized by prenatal and postnatal growth retardation, short stature, cortical thickening and medullary stenosis of the long bones, absent diploic space in the skull bones, hypocalcemia due to the hypoparathyroidism, small hands and feet, delayed mental and motor development, intellectual disability, dental anomalies, and dysmorphic features, including prominent forehead, small deep-set eyes, beaked nose, and micrognathia.

Hypoparathyroidism-retardation-dysmorphism syndrome (HRDS) is an autosomal recessive multisystem disorder characterized by intrauterine and postnatal growth retardation, infantile-onset hypoparathyroidism that can result in severe hypocalcemic seizures, dysmorphic facial features, and developmental delay (summary by Padidela et al., 2009 and Ratbi et al., 2015).