ESPE Abstracts

Background: A new classification of pseudohypoparathyroidism is available (Thiele et al. 2016, J Endocrinol). The phenotype variability of inactivating PTH/PTHrP Signaling Disorders (iPPSD, former pseudohypoparathyroidism) cases is still very challenging, even for experts. Thus, it is crucial to collect data in a centralized manner for future investigation.

Methods: The EuRRECa/EuRR-Bone registries are the first and only that adopted the new iPPSD nomenclature. In a second phase, the registries iPPSD study group conducted a secondary survey, gathering details on diagnostic procedures, phenotypic and genotypic presentation of the reported cases between 2018 and 2021. The high percentage of responders motivated us to create a condition-specific module that addresses all the medical aspects required for an adequate documentation of iPPSD cases.

Results: During the secondary survey, we obtained feedback on 77 % of the e-REC cases. 76 % had a confirmed diagnosis of iPPSD. PTH (68%) and TSH resistance (64%) were the most common biochemical findings, while majority of genetically confirmed cases presented with a loss of function mutation in the GNAS gene (maternal allele- iPPSD2). Since the secondary survey, due to active promotion of the registry at different scientific events and on social media, the number of reported cases increased substantially in the last three years. At this moment, 75 iPPSD cases (63 pediatric) from 17 countries are documented in e-REC, 46 of the patients having a confirmed iPPSD diagnose (35 children). Twenty-nine cases (19 female) are documented also in the Core-Registry, 52 % having iPPSD2 (PHP type 1A) as diagnosis. 50% of all cases were diagnosed using the combination of clinical, biochemical and genetic data. Four out of 12 patients were diagnosed rather late, after the age of six. Seven patients have at least one medical outcome report in the disease-specific module, increasing the amount of medical information collected in the Core-Registry.

Conclusion: Centralized, high-quality registries, with condition-specific modules are necessary for rare diseases in order to increase the amount of medical information and thus, the statistical power of research studies. An increase in interest regarding active participation in the registry has been observed in the last years, but there is still a need for more detailed data documentation, which can only be reached by increasing the medical information in the core and in the condition-specific module. We strongly believe research in this field will benefit immensely, once awareness within the ESPE community for adding data is reached.