Analysis of AP2S1, a calcium-sensing receptor regulator, in familial and sporadic isolated hypoparathyroidism.

Background: Except after neck surgery, hypoparathyroidism is a rare disease caused by defects in genes involved in parathyroid gland development (TBX1/22q11.2 del, GCMB, GATA3, TBCE) or function [calcium sensing receptor (CASR), GNA11, PTH], or the autoimmune polyglandular syndrome type 1 (AIRE). Approximately 90% of sporadic cases and 30% of familial cases of isolated hypoparathyroidism remain unexplained. Recurrent missense mutations in AP2S1, a calcium-sensing receptor regulator, have been recently identified in familial hyperparathyroidism. Aim: The aim of the study was to investigate AP2S1 as a putative hypoparathyroidism-causing gene. Methods: Sequencing analysis and quantitative genomic PCR of the AP2S1 gene in a large cohort of 10 index cases (from nine families) and 50 sporadic cases affected with isolated hypoparathyroidism were investigated. Results and Conclusions: None of the 60 patients presented with nucleotidic changes or copy number variation in the AP2S1 gene, thereby excluding AP2S1 def...