Clinical and genetic analysis of pseudohypoparathyroidism complicated by hypokalemia: a case report and review of the literature

Atypical presentation of pseudohypoparathyroidism with absence of mutations in the GNAS gene: a case report

BACKGROUND

This case report aimed to broaden the understanding of pseudohypoparathyroidism (PHP) manifestations when typical mutations in the GNAS gene are absent. The clinical, biochemical, and genetic investigations of a PHP case revealed diagnostic challenges and emphasized the importance of comprehensive genetic analysis for early diagnosis and appropriate management, as well as improved patient outcomes.

CASE PRESENTATION

The case involved a 21-year-old man who has experienced recurrent limb convulsions and episodes of altered consciousness since the age of eight. Recent assessments during frequent hospitalization uncovered findings consistent with PHP, including hypocalcemia, hyperphosphatemia, elevated parathyroid hormone level, and short stature. Notably, genetic testing did not reveal mutations in the GNAS gene, which could be typically associated with PHP. Diagnostic tests revealed mild abnormalities in the electroencephalogram and multiple abnormal signals in brain magnetic resonance imaging, specifically in the caudate, lenticular, dentate, and thalamus nuclei. Cranial computed tomography scan confirmed symmetrical calcifications in the basal ganglia. Biochemical analysis revealed severely altered calcium and phosphorus metabolism. Routine endocrine and neurological evaluations yielded results within normal ranges. Genetic testing identified a novel missense mutation in the GHSR gene, which has not been reported in the database and may reasonably explain some of the patient's phenotypic features.

CONCLUSIONS

While mutations in the GNAS gene are the primary genetic markers for PHP, the presence of other genetic mutations in some cases complicates the clinical analysis. This case highlights the need for a comprehensive genetic screening approach in patients with PHP-like symptoms who do not exhibit mutations in the GNAS gene, to avoid misdiagnosis and ensure timely intervention.

CLINICAL TRIAL NUMBER

Not applicable.

Hypocalcemic Tetany Transiently "Cured" by Pregnancy: A Case Report

Hypocalcemia is an uncommon electrolyte abnormality. We evaluated a young woman with episodes of recurrent symptomatic hypocalcemia which had started in her late teens. She was hypertensive and laboratory evaluation revealed an elevated PTH, elevated phosphate, and decreased renal phosphate excretion along with low ionized calcium levels. Her renin and aldosterone levels were elevated. While the response to treatment with calcium and 1,25 vitamin D was modest, her laboratory values and symptoms improved significantly during pregnancy and then recurred post-delivery. Based on clinical and laboratory features, we made a diagnosis of pseudohypoparathyroidism type Ib (PHP1B). Her genomic DNA revealed broad methylation changes at the GNAS locus which encodes the alpha-subunit of the stimulatory G protein (Gαs) without evidence for a deletion or duplication, consistent with PHP1B. Analyses of several microsatellite markers on chromosome 20 performed on our patient and her parents provided no evidence for paternal uniparental isodisomy/heterodisomy of chromosome 20q13.3 (patUPD20q). The approach to hypocalcemia; classification, clinical features, and genetic/epigenetic basis for pseudohypoparathyroidism; alterations of mineral metabolism in PHP1B and pregnancy; and implications for the high renin and aldosterone levels and hypokalemia are discussed.

A Case of Pseudohypoparathyroidism Misdiagnosed as Idiopathic Epilepsy for 5 Years: Clinical Analysis and Follow-up Outcomes

We report a 15-year-old Chinese girl who presented with intermittent seizure episodes and had been misdiagnosed as having idiopathic epilepsy 5 years previously. Laboratory testing revealed hypocalcemia, hyperphosphatemia, and a high parathyroid hormone (PTH) concentration. She was subsequently shown to have pseudohypoparathyroidism type Ib (PHPIb) based on the results of methylation analysis of the GNAS gene, which showed a loss of methylation of the differentially methylated regions (DMR) of GNAS-AS1, GNAS-XL, and GNAS-A/B; and a gain of methylation of the DMR of the GNAS-NESP55 region. We adjusted the patient's medication by prescribing calcium and calcitriol supplements, and gradually reduced the doses of antiepileptic drugs, until they had been completely discontinued. As a result, the patient did not experience any further seizures or epileptiform symptoms; and had normal plasma calcium, phosphorus, and 25-hydroxyvitamin D concentrations and 24-hour urinary calcium excretion. In addition, her PTH concentration gradually normalized over 12 months, and no urinary stones were found on ultrasonographic examination. In conclusion, the clinical presentation of PHP is complex, and the condition is often misdiagnosed. The diagnosis and follow-up of the present patient have provide valuable insights that should contribute to informed clinical decision-making and the implementation of appropriate treatment strategies.

Fahr Syndrome Secondary to Pseudohypoparathyroidism

Fahr syndrome is a rare neurologic disorder, usually affecting young and middle-aged adults, that can present with symptoms ranging from extrapyramidal to neuropsychiatric abnormalities. Pseudohypoparathyroidism (PHP), characterized by parathyroid hormone (PTH)-resistance or PTH-unresponsiveness at target organs, is associated with Fahr syndrome and typically presents with hypocalcemia. The following case presents a 39-year-old-woman with PHP complicated by symptomatic hypocalcemia, hypokalemia, and movement disturbances, who had computed tomography imaging showing basal ganglia calcifications consistent with Fahr syndrome. She initially presented with headache and was hospitalized for hypertensive emergency and severe hypocalcemia. Examination, including the neurologic examination, was unrevealing aside from hypertension and central adiposity. Laboratory tests were consistent with PHP, showing hypocalcemia with elevated PTH, and negative for hyperaldosteronism. Management of hypocalcemia consisted of intravenous calcium infusion, oral calcium carbonate, oral vitamin D3, and oral calcitriol. Patients with severe hypocalcemia and elevated PTH who present with new neurological symptoms despite normal general neurologic examination may warrant consideration for brain imaging to evaluate for Fahr syndrome. Further investigations are necessary to determine the prevalence of Fahr syndrome and hypokalemia in patients with PHP, explore if these findings are significantly associated with PHP-1b subtype, and ultimately inform potential new screening pathways for these patients.