Pseudopseudohypoparathyroidism (pseudoPHP) is an inherited disorder that is caused by a mutation in the G_?s gene imprinted on the paternal chromosome. As such, a haploinsufficiency results similar to pseudohypoparathyroidism 1A, which is caused by a similar defect on the corresponding maternal chromosome. However, unlike pseudohypoparathyroidism 1A, which presents with all the symptoms of hypoparathyroidism except the low parathyroid hormone levels, pseudopseudohypoparathyroidism presents only with the skeletal defects and none of the defects in calcium and phosphate homeostasis. ^[1] Patients generally have normal calcium and phosphate levels and normal parathyroid hormone levels. As such, it is sometimes considered a variant of Albright hereditary osteodystrophy.^[2]

Presentation

It has mild or no manifestations of hypoparathyroidism or tetanic convulsions.

Short stature may be present.^[3]

Hormone resistance is not present.^[4]

Obesity is less common in pseudopseudohypoparathyroidism than in pseudohypoparathyroidism.^[5]

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 interited paternal chomosome will be changed to the maternal pattern in the mother's ovum during meiosis.

Linguistic significance

At 30 letters, the English name of the disorder is one of the candidates for being the longest word in English.^[6]

See also

• parathyroid hormone
• GNAS1

References

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