Čes-slov Pediat 2024, 79(89):S25-S29 | DOI: 10.55095/CSPediatrie2024/054

Pseudohypoparathyroidism type Ia and pseudopseudohypoparathyroidismOriginal Papers

Renata Pomahačová, Petra Paterová, Eva Nykodýmová, Petr Polák, Josef Sýkora

Dětská klinika, Lékařská fakulta, Univerzita Karlova, Fakultní nemocnice v Plzni

Pseudohypoparathyroidism type Ia (PHP Ia) and pseudopseudohypoparathyroidism (PPHP) are rare autosomal dominantly inherited diseases caused by a heterozygous inactivating mutation of the GNAS1 gene encoding the stimulatory α-subunit of the G protein. The development of these diseases is related to genomic imprinting. Patients with PHP Ia have symptoms of Albright hereditary osteodystrophy (AHO) and hormone resistance to thyroid-stimulating hormone (TSH) and parathyroid hormone (PTH). Patients with PPHP have symptoms of AHO without hormone resistance. Typical symptoms of AHO in PHP Ia are early onset of obesity in infancy and subcutaneous calcifications. Resistance to TSH can be present at birth or in early infancy. Resistance to PTH, on the other hand, develops later during childhood. Late diagnosis of PHP Ia is a risk of life-threatening hypocalcemic seizures. Knowledge of AHO symptoms together with hypothyroidism can lead to early diagnosis. We describe our own experience and the latest knowledge about PHP Ia and PPHP according to the first international consensus of 2018, focusing on clinical symptoms, endocrine disorders, genetic background and disease management.

Keywords: pseudohypoparathyroidism type Ia, pseudopseudohypoparathyroidism, Albright hereditary osteodystrophy, GNAS1 gene, hormone resistance

Accepted: September 25, 2024; Published: December 1, 2024  Show citation