Abstract
PHP-I is a genetic disease characterized by target organ resistance to the action of parathyroid hormone (PTH) and sometimes of other peptide hormones. Recent evidence suggests that the adenylate cyclase defect in PHP-I resides in the guanine nucleotide binding regulating protein (N-protein), which mediates the response of the adenylate cyclase to peptide hormones.
The present study describes a 15 yr old girl (karyotype XX) with hypocalcemia, elevated serum iPTH, decreased urinary cyclic AMP response and Albright's osteodystrophy who presented with delayed puberty. Despite accelerated bone age (17 yr at the chronological age of 13 yr) the girl did not go beyond a Tanner stage III. Serum estradiol was low (20-35 pg/ml) despite elevated basal and LHRH-stimulated LH and FSH secretion suggesting partial gonadotropin resistance of the ovary. Target organ resistance to the action of TSH, ACTH and ADH as well as prolactin deficiency could be excluded. Measurement of N-protein activity (kindly done by H. Radeke, Hannover, FRG) in membrane extracts of erythrocytes, using cyc − S49 mouse lymphoma cells gave normal results (105.9 %, normal 100 ± 40 %). It is concluded that the disease in this girl is caused by a molecular defect different from other patients with PHP-I affecting accumulation of cyclic AMP in the target organs of PTH and the gonadotropins.
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Kruse, K. Delayed puberty in pseudohypoparathyroidism type I (PHP-I). Pediatr Res 18, 1224 (1984). https://doi.org/10.1203/00006450-198411000-00139
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DOI: https://doi.org/10.1203/00006450-198411000-00139