The clinical diagnosis of PHP1a is based on the presence of PTH resistance (i.e., hypocalcaemia, hyperphosphataemia, and elevated serum PTH) in association with the features of AHO, which includes short stature, obesity, subcutaneous calcification, mental retardation, round facies, and brachydactyly [Thakker, 2011]. This evidence concerns the gene PTH and hyperphosphatemia.