Parental mosaicism at GNAS gene

iPPSD2 is a rare inherited autosomal dominant endocrine disorder caused by inactivating GNAS pathogenic variants. A high percentage of de novo cases has been suggested. In rare cases, parental mosaicism has been described, but its real frequency is unknown. The main objective of this work is to stablish de possibility of mosaicism in progenitors of patients with iPPSD2 caused by variants of de novo or unknown origin. This would help in genetic counselling giving information about the risk of recurrence and to get an idea of the possibility of this option for genetically undiagnosed patients.