[Different expression of the Asn264LysfsX35 mutation of the GNAS gene in a family with pseudohypoparathyroidism.].

Pseudohypoparathyroidism (PHP) is a heterogeneous group of endocrine diseases characterised by hypocalcaemia, hyperphosphataemia and resistance to PTH. There are different forms of PHP. PHP-Ia is the most frequent form and shows multi-hormonal resistance, GNAS (Gs(α)) mutations and signs of Albright́s hereditary osteodystrophy (AHO). PseudoPHP (PPHP) have isolated AHO without hormonal resistance and it is also caused by GNAS mutations. We present a family that share the same inactivating GNAS mutation (Asn264LysfsX35); the mother being affected with PPHP and the two daughters with PHP-Ia. We discuss the different clinical phenotypes and the dominant mode of inheritance with genetic imprinting where the phenotype of the offspring depends on the sex of the parent affected.