Unrecognized Pseudohypoparathyroidism Type 1A as a Cause of Hypocalcemia and Seizures in a 64-Year-Old Woman

A patient with pseudohypoparathyroidism type 1A previously misdiagnosed as hereditary multiple exostosis: A case report

Pseudohypoparathyroidism type 1A (PHP1A), a rare hereditary disorder, is featured by end-organ resistance to parathyroid hormone and Albright's hereditary osteodystrophy. Heterozygous mutation of guanine nucleotide-binding protein α stimulating (GNAS) gene causes the half decreased bioactivity of the Gsα protein levels. Due to the diverse early clinical manifestations of PHP1A, a diagnosis of PHP1A is often easily overlooked and misdiagnosis or missed diagnosis is common. The present study described a girl who was initially diagnosed with hereditary multiple exostoses, but was afterwards confirmed with PHP1A. Moreover, genetic analysis indicated a new mutation (c2277deIC) of the gene.

Fahr syndrome discovered in adulthood revealing a rare GNAS mutation in pseudohypoparathyroidism type 1a in a Tunisian family

Pseudohypoparathyroidism (PHP) indicates a rare heterogeneous group of disorders characterized by hypocalcemia, hyperphosphatemia, increased serum concentration of parathyroid hormone (PTH), and insensitivity to the biologic activity of PTH. One of its most common types is PHP‐1a. In this report, we present a familial PHP‐1a and a novel mutation of the GNAS gene.

PHP1a is one of the rare and little‐known pathologies that can take a long time to be discovered. It associates a particular morphotype, subcutaneous calcifications and bone and renal resistance to parathormone. It is an inherited condition, which results from an abnormality in the GNAS gene. It is usually diagnosed in childhood. and few studies have addressed its natural history. Our report illustrates the natural history of a patient with PHP1A, which went undiagnosed until the age of 31 years. Through this clinical case, we emphasize the importance of a complete phosphocalcic balance in order to find and recognize the typical biochemical alterations associated with this pathology (hypocalcemia, hyperphosphatemia and high levels of PTH), the need for a detailed clinical examination because the phenotypic appearance often escapes notice and the identification of the responsible mutation in the index case is useful for screening other family members avoiding late diagnosis.

Basal ganglia calcification in hypoparathyroidism and pseudohypoparathyroidism: local and systemic metabolic mechanisms

BACKGROUND

Hypoparathyroidism and pseudohypoparathyroidism are rare disorders of mineral metabolism which may be associated with soft tissue calcification in the basal ganglia in the brain, and occasionally the skin and other tissues. The basal ganglia are the most common sites of calcification in the central nervous system in these disorders, and were first associated with this manifestation in a report from the Mayo Clinic in 1939. The reasons why the basal ganglia are a common site of soft tissue calcification in these rare disorders has been a matter of investigation for many years.

FINDINGS

Due to recent increased understanding of phosphate transport and new insights gained from mRNA expression in the basal ganglia, the pathophysiology of basal ganglia calcification (BGC) is now clearer. There is evidence that the absence of parathyroid hormone in hypoparathyroidism may play a direct role, but this is clearly not the case in pseudohypoparathyroidism, which is associated with increased parathyroid hormone levels. Maintaining the calcium/phosphorus ratio as close to normal as possible, and maintaining normal serum phosphate levels, may help mitigate the progression of BGC. There is no evidence of regression of BGC with conventional treatment, and long-term data with adjunctive or replacement therapy with parathyroid hormone or its analogues are not yet available.

PURPOSE OF THE REVIEW

This review will focus on the pathophysiology of BGC in hypoparathyroidism and pseudohypoparathyroidism, and review the proposed pathophysiologic mechanisms, as well as the clinical implications of BGC on patient quality of life.