A Case of GNAS1 Mutation in Pseudohypoparathyroidism Type Ia

ABSTRACT

Pseudohypoparathyroidism (PHP) is a group of genetic disorders in which the kidneys fail to respond to parathyroid hormone. Genetic defects in the GNAS complex locus lead to reduced Gsalpha (alpha-subunit of the heterotrimeric stimulatory G protein) activity in PHP type Ia patients. These patients exhibit characteristics of Albright hereditary osteodystrophy (AHO) and hypocalcemia, increased parathyroid hormone, and resistance to other Gsalpha protein-coupled hormones. AHO has a wide range of manifestations such as short stature, obesity, round face, subcutaneous ossification, and bone shortening in the hands and feet. In this study, we present the case of a 47-yr-old woman who was diagnosed with PHP type Ia with AHO. She showed tetany, dizziness, irritability to light, decreased visual acuity, cognitive impairment, and motor dysfunction. Direct sequencing identified a heterozygous missense mutation in exon 6 (c.466G>A, p.Asp156Asn) in GNAS1. To our knowledge, this case is the first report in Korea of PHP type Ia caused by a heterozygous missense mutation in exon 6 (c.466G>A, p.Asp156Asn) in GNAS1.