Pseudopseudohypoparathyroidism

Pseudopseudohypoparathyroidism (pseudoPHP) is an inherited disorder, named for its similarity to pseudohypoparathyroidism in presentation. The term pseudopseudohypoparathyroidism is used to describe a condition where the individual has the phenotypic appearance of pseudohypoparathyroidism type 1a, but is biochemically normal.

It is sometimes considered a variant of Albright hereditary osteodystrophy.

It was characterized in 1952 by Fuller-Albright as "pseudo-pseudohypoparathyroidism" (with hyphen).

Presentation
Pseudopseudohypoparathyroidism can be best understood by comparing it to other conditions:

Hormone resistance is not present in pseudopseudohypoparathyroidism. Short stature may be present. Obesity is less common in pseudopseudohypoparathyroidism than in pseudohypoparathyroidism. Osteoma cutis may be present.

Inheritance
A mother who has inherited pseudopseudohypoparathyroidism from her father may in turn pass along pseudohypoparathyroidism 1A to her children as the imprinting pattern on the inherited paternal chomosome will be changed to the maternal pattern in the mother's ovum during meiosis.

Pseudopseudohypoparathyroidism and pseudohypoparathyroidism both involve the same GNAS gene, but pseudopseudohypoparathyroidism has normal calcium homeostasis because of the normal maternal allele in the kidney.

Linguistic significance
At 30 letters, the English name of the disorder is one of the candidates for being the longest word in English.