A type of pseudohypoparathyroidism with characteristics of localized resistance to parathyroid hormone (PTH) mainly in the renal tissues which manifests with hypocalcemia, hyperphosphatemia and elevated PTH levels. About 60-70% of patients also present with elevated TSH levels due to TSH resistance. Severity of symptoms can vary greatly between patients and even among kindreds. The majority of cases are sporadic, but an autosomal dominant transmission has also been described. About 70% of patients display methylation defects, sporadic or genetic-based, at GNAS (20q13.2-q13.3) differentially methylated regions (DMRs).