Background: Disorders related to an impairment in parathyroid hormone (PTH) signaling pathway are historically classified under the term pseudohypoparathyroidism (PHP), that now encompasses rare, related but highly heterogeneous diseases with demonstrated (epi)genetic causes. The actual classification is based on the presence or absence of specific clinical and biochemical signs together with an in vivo response to exogenous PTH and an in vitro assay of Gsα protein activity. However, this classification does not take into consideration other related diseases like acrodysostosis (ACRDYS) or Progressive Osseous Heteroplasia (POH), as well as recent associations to phenotypes and genetic/epigenetic background of the different subtypes.
Objective and hypotheses: The EuroPHP network met on three different occasions with the major goal of developing a new classification that encompasses all disorders with an impairment in PTH and/or PTHrP cAMP-mediated pathway.
Method: An extensive review of the literature was performed. Several meetings were organized to discuss about a new, more effective and accurate way to describe disorders related to abnormalities of the PTH signaling pathway. This led to the realization of a novel terminology and classification of these disorders.
Results: After a selection of major and minor criteria to consider for the diagnosis of these disorders, we proposed to group them under the term of inactivating PTH/PTHrP signaling disorders, abbreviated as iPPSD. This terminology: i) defines the common mechanism responsible for all diseases, ii) does not require a confirmed genetic defect, iii) avoids ambiguous terms like pseudo, iiii) eliminates the clinical or molecular overlap between diseases.
Conclusion: We believe that the use of this nomenclature and classification will facilitate the development of rationale and comprehensive international guidelines for the diagnosis and treatment of iPPSDs.
10 - 12 Sep 2016
European Society for Paediatric Endocrinology