MUTATION IN THE GENE ENCODING THE STIMULATORY G-PROTEIN OF ADENYLATE-CYCLASE IN ALBRIGHTS HEREDITARY OSTEODYSTROPHY

Albright's hereditary osteodystrophy is an autosomal dominant disorder characterized by a short stature, brachydactyly, subcutaneous ossifications, and reduced expression or function of the α subunit of the stimulatory G protein (Gsα) of adenylate cyclase, which is necessary for the action of parathyroid and other hormones that use cyclic AMP as an intracellular second messenger. We identified a unique Gsα protein in erythrocytes from two related patients with Albright's hereditary osteodystrophy and reduced Gsα bioactivity. The Gsα variant was recognized by a carboxyl terminal—specific Gsα antiserum but not by polyclonal antiserums specific for the amino terminus of Gsα. To investigate the molecular basis for this structurally abnormal Gsα protein, we studied the Gsα gene by restriction-endonuclease analysis. DNA from the two patients had an abnormal restriction-fragment pattern when digested with Ncol, which was consistent with loss of an Ncol restriction site in exon 1 of one Gsα allele. Amplification of a 260-base-pair region that includes exon 1 of the Gsα gene and direct sequencing of the amplified DNA revealed an A-to-G-transition at position +1 in one Gsα allele from each of the two patients. This mutation converts the initiator ATG (methionine) codon to GTG (valine), blocking initiation of translation at the normal site. Translation of the abnormal Gsα messenger RNA would result in the synthesis of a truncated Gsa molecule lacking the amino terminus. We conclude that in at least some patients with Albright's hereditary osteodystrophy, the disease is caused by a single-base substitution in the Gsα gene and is thus due to an inherited mutation in a human G protein. (N Engl J Med 1990; 322:1412–9.). © 1990, Massachusetts Medical Society. All rights reserved.