Determination of Circulating Autotaxin in Patients With GNAS or PTH Abnormalities

  • End date
    Mar 10, 2024
  • participants needed
  • sponsor
    Hospices Civils de Lyon
Updated on 24 March 2021


PTH secretion defects (grouped under the name hypoparathyroidism) are due to abnormalities in the PTH gene, abnormalities in the development of the parathyroid glands which synthesize PTH or abnormalities of the calcium sening receptor whose role is to adapt PTH level to ambient calcium level.

In contrast, primary hyperparathyroidism in children is also exceptional; expressed by hypercalcemia, with a renal and bon risk.

Pseudo-hypoparathyroidism, now known under the term inactivating PTH / PTHrP Signaling Disorder or iPPSD, are rare pathologies characterized by resistance to the action of PTH sometimes associated with other symptoms, in particular chondrodysplasia. They are linked to a defect in the action of a factor in the signaling pathway of G protein-coupled receptors that activate the production of cyclic AMP (cAMP). IPPSDs are most often due to a molecular defect in the GNAS gene, subject to parental imprint.

Fibrous dysplasia / McCune-Albright syndrome is a rare disease caused by somatic "gain-of-function" mutations in the GNAS gene located on chromosome 20q13 leading to activation of the protein Gs and inappropriate production of intracellular cyclic adenosine monophosphate (cAMP). The clinical phenotype is determined by the location and extent of the tissues affected by this mutation.

Autotaxin (ATX) is a protein secreted by different tissues including the liver, fatty tissue, and bone. Today, ATX is described as the major source of LPA in the bloodstream. LPA interacts with one of its receptors on the surface of the cell membrane. Depending on the receptor engaged, one or more G subunits (G12 / 13, GQ, Gi / o or Gs) will activate multiple cell signaling pathways.

In bone, ATX is expressed by osteoclasts and osteoblasts. Recent laboratory data have shown that PTH stimulates ATX expression in osteoblasts in a dose-dependent manner.

The objective of this study is to provide clinical proof of concept that the PTH / Gs / ATX pathway is truly significant in physiology and pathology, by studying the full spectrum of PTH and GNAS pathologies. If this proof of concept is obtained, therapeutic applications will probably be possible in the long term.

Condition Adult Children, Polyostotic fibrous dysplasia, McCune-Albright Syndrome, Hyperparathyroidism, Hyperparathyroidism, Hyperparathyroidism (Pediatric), PARATHYROID DISORDER, Parathyroid Disorders, Parathyroid Disease, Hypoparathyroidism, Hypoparathyroidism, Pseudohypoparathyroidism, Fibrous Dysplasia, Hyperparathyroidism (Pediatric), McCune-Albright Syndrome, Parathyroid Disorders, Parathyroid Disease, albright syndrome, bone fibrous dysplasia
Treatment Blood sample
Clinical Study IdentifierNCT04671719
SponsorHospices Civils de Lyon
Last Modified on24 March 2021


Yes No Not Sure

Inclusion Criteria

Pediatric patients
Children from 10 to 18 years old
Patients with Fibrous dysplasia / McCune-Albright syndrome,hypoparathyrodism, hyperparathyrodism, or iPPSD, from References Centers for rare diseases (Calcium and phosphate metabolism, constitutional bone diseases) followed at hpital Femme Mre Enfant (Bron) or at hpital Bictre Paris Saclay (Paris)
Patients and parent / holder of parental authority who have been informed of the study and do not object to participate
Patients > 18 years old
Patients with Fibrous dysplasia / McCune-Albright syndrome, followed in reference center for constitutional bone diseases at hpital Edouard Herriot (Lyon)
Patients who have been informed of the study and do not object to participate

Exclusion Criteria

Children < 8 kg
Patient with hepatic disease
Patients under tutorship or curatorship
Pregnant and / or breastfeeding woman
Patient deprived of liberty
Patient in emergency situation who can not agree to participate
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