Pseudohypoparathyroidism: focus on cerebral and renal calcifications

Context Pseudohypoparathyroidism (PHP) is a group of disorders characterized by hypocalcemia, hyperphosphatemia and elevated PTH levels, as a result of end-organ resistance to PTH. Objective To describe a cohort of 26 patients with PHP, followed in a single tertiary center. Design Clinical, biochemical, radiological and genetic analysis of the GNAS gene were collected in 26 patients recruited since 2002. Results Ten patients harbored a GNAS mutation, 15 epigenetic abnormalities at the GNAS locus and one was negative. According to clinical, biochemical and genetic features, patients were classified as PHP1A, PHP1B and PPHP. Patients with PHP1A had an earlier diagnosis and more cases with family history, Albright hereditary osteodystrophy features (AHO), hormonal resistance and hypertension. Obesity was a common feature. No difference in biochemical values was present among PHP1A and PHP1B. Intracerebral calcification occurred in 72% of patients with no difference among PHP1A and PHP1B subgroups. No significant difference was observed between patients with and without intracerebral calcification for the time-weighted average values of total serum calcium, phosphate, calcium-phosphate product and PTH fold increase. A borderline association between cerebral calcification and age at the time of diagnosis (P =0.04) was found in the whole cohort of patients. No renal calcifications were found in the overall cohort. Conclusions Patients with PHP1A more frequently have AHO features as well as hypertension compared to PHP1B. PHP patients presented a high rate of intracerebral calcification with no significant difference between subgroups. No increased risk of renal calcifications was also found in the entire cohort