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pseudohypoparathyroidism type 1C - Clinical Profile, Genes & Research | Kisho | Kisho

Rare Disease

pseudohypoparathyroidism type 1C

MONDO:0012911

Also known as:pseudohypoparathyroidism IcPHP1CPhp 1C

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Overview

A rare type of pseudohypoparathyroidism (PHP) characterized by resistance to parathyroid hormone (PTH) and other hormones, which manifests with hypocalcemia, hyperphosphatemia and elevated PTH levels, a constellation of clinical features collectively termed Albright's hereditary osteodystrophy (AHO), but normal activity of the stimulatory protein G (Gs alpha).

GeneticsAutosomal dominant · GNAS (chr 20)

Clinical Trials1 registered · 1 recruiting

ResearchLimited published research (6 articles)

Clinical Presentation

Built from Human Phenotype Ontology (HPO) phenotype annotations and GeneReviews clinical descriptions. Features represent findings documented across known cases — not an exhaustive list of possible symptoms.

Features include always present findings: Pseudohypoparathyroidism and Elevated circulating thyroid-stimulating hormone concentration; and very common findings: Low urinary cyclic AMP response to PTH administration, Elevated circulating parathyroid hormone level, Hyperphosphatemia, and Hypocalcemia and others. 60 total HPO annotations.

Organ System	Phenotype Count	Example Features
Brain and nerves	14	Seizure, Difficulty with thinking and memory (cognitive impairment), Intellectual disability

Genetic Landscape

Assembled from HGNC gene records, ClinGen gene-disease validity evidence, and ClinVar pathogenic variant data. Validity classifications reflect the strength of published evidence linking each gene to this disease.

GNAS encodes GNAS complex locus (1,037 aa). Guanine nucleotide-binding proteins (G proteins) function as transducers in numerous signaling pathways controlled by G protein-coupled receptors (GPCRs). Highest expression in Pituitary (1,324 TPM) and Thyroid (727.3 TPM).

Pseudohypoparathyroidism type 1C is associated with mutations in the GNAS gene on chromosome 20.

The GNAS protein participates in G alpha (s):GTP:SRC dissociates and G alpha (s):GTP:SRC catalyzes SRC to p-Y419-SRC pathways.

GNAS is classified as a druggable target (Clinically Actionable, Drug Resistance, Druggable Genome, G Protein Coupled Receptor, and Transporter categories) with score 1.5.

Diagnosis

Drawn from GeneReviews diagnostic guidelines, newborn screening panel status (RUSP), and ClinGen gene-disease validity classifications. Reflects current clinical evidence and consensus where available.

GeneReviews

Diagnostic Criteria

No specific clinical criteria establish the diagnosis of a disorder of GNAS inactivation.

Suggestive Findings

A disorder of GNAS inactivation should be suspected in individuals with the following phenotypes. Pseudohypoparathyroidism Ia (PHP-Ia) and pseudohypoparathyroidism Ic (PHP-Ic). The most readily recognized form of PHP is PHP-Ia, which has clinical and endocrine features similar to PHP-Ic. Note: PHP-Ic differs from PHP-Ia on the basis of normal functional activity of Gs (the protein encoded by GNAS) determined in some biochemical assays based on receptor-independent activation of Gs . PHP-Ia and PHP-Ic should be suspected in individuals with some of the following clinical and endocrine findings (which may emerge over time):

Treatment

Compiled from FDA-approved drug records, orphan drug designations, and FDA Adverse Event Reporting System (FAERS) safety data. GeneReviews management guidance is included where available.

No approved treatments are currently available for pseudohypoparathyroidism type 1C. The disease remains an area of unmet medical need.

GeneReviews

Management Guidelines

Evaluations Following Initial Diagnosis

To establish the extent of disease and needs in an individual diagnosed with a disorder of GNAS inactivation, the following evaluations are recommended:

Assessment of height, weight, body mass index, growth velocity, and pubertal development

Prognosis

Based on GeneReviews surveillance recommendations, HPO phenotype frequency and severity annotations, and published prevalence estimates from Orphanet and OMIM.

GeneReviews

Surveillance Guidelines

Surveillance includes the following:

Once the diagnosis is established, annual monitoring for endocrine abnormalities with measurement of serum concentration of PTH, calcium, and phosphate; TSH and free T4, and urinary calcium excretion (either 24-hour urine collection or random urine collections for determination of the calcium/creatinine ratio). These studies should be begun as soon an individual begins treatment, and may be performed more frequently in growing children who may experience increasing requirements for thyroid hormone and/or activated forms of vitamin D.

Research Landscape

Sourced from ClinicalTrials.gov and PubMed. Publication types are classified using NLM-curated article metadata; research type breakdowns reflect the nature of published work for this disease.

1 clinical trial registered, 1 recruiting. Interventions under study include drug therapy. Pipeline includes 1 PHASE4. Research is primarily sponsored by academic and government institutions.

8 publications have been identified in PubMed for pseudohypoparathyroidism type 1C. Kisho has analyzed 6 by research type. Research spans Review / Meta-Analysis (50%), Case Report / Case Series (17%), and Clinical Trial Publication (17%).

Recent Publications

Jiang S (2026). [PMID: 41707176](https://pubmed.ncbi.nlm.nih.gov/41707176/). *JMIR mHealth and uHealth*. [Review / Meta-Analysis]
Sahay R (2026). [PMID: 42070788](https://pubmed.ncbi.nlm.nih.gov/42070788/). *Diabetes Obes Metab*. [Clinical Trial Publication]
Bodner E (2025). [PMID: 39854703](https://pubmed.ncbi.nlm.nih.gov/39854703/). *Journal of medical Internet research*. [Review / Meta-Analysis]
Demertzidou E (2025). [PMID: 41222894](https://pubmed.ncbi.nlm.nih.gov/41222894/). *Hormones (Athens, Greece)*. [Case Report / Case Series]
Redfern-Nichols T (2025). [PMID: 40392940](https://pubmed.ncbi.nlm.nih.gov/40392940/). *Science signaling*. [Basic Science / Preclinical]

Data assembled from 8 of 12 sources · Last updated Sep 19, 2026, 4:29 PM UTC

MONDOHPOClinicalTrials.govFDAPubMedHGNCClinVarClinGenGeneReviewsOrphanetOMIMRUSP

Medical References

External Resources

OMIM

Online Mendelian Inheritance in Man

OMIM:612462

Orphanet

European rare disease database

Orphanet:79444

GARD

Genetic and Rare Diseases Info Center

GARD:10681

Questions for Your Care Team

→Are any of the 1 active clinical trial a good fit for my situation?
→Should I pursue genetic testing for GNAS, and what would the results mean for my family?
→Are there specialists or centers of excellence for this condition in my area?
→Is there a patient registry I should consider joining?

← Back to All Diseases

Kisho

pseudohypoparathyroidism type 1C

Overview

Clinical Presentation

Genetic Landscape

Diagnosis

Diagnostic Criteria

Suggestive Findings

Treatment

Management Guidelines

Evaluations Following Initial Diagnosis

Prognosis

Surveillance Guidelines

Research Landscape

Recent Publications

Medical References

External Resources

OMIM

Orphanet

GARD

Questions for Your Care Team

Questions for Your Care Team

Clinical Guidance

Pseudohypoparathyroidism Ia (PHP-Ia) and PHP-Ic

Explore clinical features

Clinical Guidance

Penetrance

Differential Diagnosis

Treatment of Manifestations

Clinical Guidance

Therapies Under Investigation

Clinical Trials

pseudohypoparathyroidism type 1C

Overview

Clinical Presentation

Genetic Landscape

Diagnosis

Diagnostic Criteria

Suggestive Findings

Treatment

Management Guidelines

Evaluations Following Initial Diagnosis

Prognosis

Surveillance Guidelines

Research Landscape

Recent Publications

Medical References

External Resources

OMIM

Orphanet

GARD

Related Diseases

Questions for Your Care Team

Questions for Your Care Team

Clinical Guidance

Pseudohypoparathyroidism Ia (PHP-Ia) and PHP-Ic

Explore clinical features

Clinical Guidance

Penetrance

Differential Diagnosis

Treatment of Manifestations

Clinical Guidance

Therapies Under Investigation

Clinical Trials