A novel mutation in a case of pseudohypoparathyroidism type Ia.

Pseudohypoparathyroidism (PHP) type Ia is characterized by multiple hormone resistance; primarily parathyroid hormone (PTH) resistance and Albright's hereditary osteodystrophy (AHO) which involves skeletal and developmental defects. The AHO phenotype alone without hormone resistance is defined as pseudoPHP. A boy was first diagnosed as having both rickets and primary hypothyroidism at 2.5 months of age. His calcium level remained within normal levels after vitamin D treatment, but, elevated PTH and ALP levels and normal-high phosphate levels persisted during his follow-up by age of 2.5 years. He was admitted with hypocalcemic convulsions as well as hyperphosphatemia and elevated PTH levels suggested PTH resistance at 2.5 years of age. He and his mother were obese and had round faces, frontal bossing, small noses, flat nasal bridges, brachydactyly. His mother showed no hormonal resistance. These findings indicated that our patient had PHP type Ia and his mother had pseudoPHP. The same novel heterozygous mutation in the GNAS gene (IVS4+5G > C) was identified in both of patients.