<prompt> Which of the following statements about Pseudohypoprathyroidism is true:Caused by Gain of function inherited mutation in Gsa subunitDecreased formation of cyclic GMP is observedDecreased formation of Inositol triphosphate is observedDecreased formation of c-AMP is observed  <response>: Answer is D Decreased formation of c-AMP is observed The most common subtype of Pseudohypoparathyroidism PHP-Ia is typically associated with reduced decreased cAMP production in response to exogenous PTH Pseudohypoparathyroidism is associated with decreased formation of cyclic AMP and not decreased cyclic GM P or Inositol Triphosphate The Gs family of G-proteins use the activation of adenylate cyclase as the next step in signal transduction, to produce cyclic AMP PseudohypoparathyroidismIa is associated with loss of function mutation of Gsa subunit, and hence results in decreased formation of cyclic AMP Pseudohypoparathyroidism is associated with reduced urinary c-AMP response to PTH The term Pseudohypoparathyroidism describes a heterogeneous syndrome characterized by biochemical Hypoparathyroidism Hypocakemia Hyperphosphatemia with paradoxical increased plasma levels of PTH. This is caused by peripheral unresponsiveness to the biological action of PTH or PTH resistance. Although several subtypes of Pseudohypoparathyroidism are identified, the most common subtype of PHP PHP la is characterized by deficient urinary cyclic AMP response to administration of exogenous PTH. Failure of cAMP production in these patients after PTH infusion is believed to result from a defect in cyclic AMP mediated signal transduction from a Gsa Loss of function mutation as depicted in the figure previous heading The measurement of cyclic AMP in urine following an infusion of synthetic PTH is now used to establish a diagnosis of PTH resistance - Williams Endocrinology 111243 Pseudohypoparathyroidism is associated with a loss of function inherited G sa mutation. Endocrine diseases can result from either loss or gain of gene function acquired or inherited Pseudohypoparathyroidismla results from an inherited loss of function mutation of the Gsa subunit Gsa activating mutation Gain of function Gsa inactivating mutation Loss of function Acromegaly Pseudohypoparathyroidismla Pituitary coicotroph Adenoma Mc.Cune Albright syndrome Hyperfunctioning Thyroid Adenomas Endocrine ovarian neoplasms Taken from Principles practice of Endocrinology and Metabolism 