GNAS and pseudohypoparathyroidism type 1B: Affected members of the family with the R186H mutation presented with hypocalcemia without skeletal abnormalities, consistent with a pseudohypoparathyroidism type 1b (PHP1B) phenotype.(19) PHP1B is typically caused by mutations in the GNAS locus that lead to epigenetic reductions in Gsα protein expression in cells of certain imprinted tissues, including renal tubule cells involved in PTH1R‐mediated control of calcium and phosphate transport.(20) Until the report of the R186H mutation,(19) which we studied here, no mutation in the PTH1R has been associated with pseudohypoparathyroidism.