A Distinct Variant of Pseudohypoparathyroidism (PHP) First Characterized Some 41 Years Ago Is Caused by the 3-kb Deletion.

In 1980, Farfel and colleagues (, 1980;303:237-42) provided first evidence for two distinct variants of pseudohypoparathyroidism (PHP) that present with hypocalcemia and impaired parathyroid hormone (PTH)-stimulated urinary cAMP and phosphate excretion, either in the presence or absence of Albright's hereditary osteodystrophy (AHO). An "abnormal allele" and an "unexpressed allele" were considered as underlying defects, predictions that turned out to be correct for both forms of PHP. Patients affected by the first variant (now referred to as PHP1A) were later shown to be carriers of inactivating mutations involving the maternal exons encoding Gsα.