Omphalomesenteric duct cysts (ODC, also known as an omphalomesenteric duct remnant or vitelline cyst) are developmental defects relating to the closure of the omphalomesenteric duct. It usually disintegrates within six weeks of gestation, but remnants of the cyst can sometimes be found along the intestines or umbilicus. Any remnants can be removed via surgical means. See also
Pilomatricoma
List of cutaneous conditions


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Pathophysiology
The GNAS1 gene involved in both Pseudohypoparathyroidism type 1a and Pseudopseudohypoparathyroidism is greatly affected by imprinting. When a father who has Pseudohypoparathyroidism undergoes spermatogenesis, imprinting of the GNAS1 gene inactivates both copies of his genes: one will be Functional and the other will be defective. Tissues in the body will re-activate different copies of the GNAS1 gene selectively; the kidneys will selectively activate the (functional) maternal copy while keeping the (defective) paternally-derived gene imprinted and inactive, even in normal individuals. Since the maternally-derived GNAS1 gene is functional, renal handling of calcium and phosphate is normal, and homeostasis is maintained in Pseudopseudohypoparathyroidism. However, the rest of the tissues will instead selectively display the defective gene, resulting in haploinsufficiency of the GNAS1 product in most tissues, and giving the phenotype of Pseudohypoparathyroidism type 1a. As a result, there is also a normal response of urinary cAMP to PTH, and normal serum PTH. Diagnosis
The diagnosis is based on the presence of the Albright hereditary osteodystrophy pseudotype but without the PTH resistance. Blood tests including calcium, phosphate, and PTH will exclude other forms of Pseudohypoparathyroidism. X-rays may reveal a short fourth metacarpal. Genetic testing can confirm the diagnosis by showing GNAS gene mutation. Treatment
Treatments focuses on symptoms, with genetic counseling recommended. History
It was characterized in 1952 by Fuller Albright as "pseudo-pseudohypoparathyroidism" (with hyphen). See also
Antidisestablishmentarianism
Floccinaucinihilipilification
GNAS complex locus
Honorificabilitudinitatibus
Longest word in English
Longest words
Parathyroid hormone
Pneumonoultramicroscopicsilicovolcanoconiosis
Supercalifragilisticexpialidocious

References


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