Pseudohypoparathyroidism type Ia and pseudo-pseudohypoparathyroidism: the growing spectrum of GNAS inactivating mutations.

Pseudohypoparathyroidism (PHP) is a rare heterogeneous genetic disorder characterized by end-organ resistance to parathyroid hormone due to partial deficiency of the α subunit of the stimulatory G protein (Gsα), encoded by the GNAS gene. Heterozygous inactivating GNAS mutations lead to either PHP type Ia (PHP-Ia), when maternally inherited, or pseudo-pseudohypoparathroidism (PPHP), if paternally derived. Both diseases feature typical physical traits identified as Albright's hereditary osteodystrophy in the presence or absence of multihormone resistance, respectively. GNAS mutations are detected in 60-70% of affected subjects, most patients/families harbor private mutations and no genotype-phenotype correlation has been found to date. We investigated Gsα-coding GNAS exons in a large panel of PHP-Ia-PPHP patients collected over the past decade in the two Italian referring centers for PHP. Of 49 patients carrying GNAS mutations, we identified 15 novel mutations in 19 patients. No apparent correlation was found between clinical/biochemical data and results of molecular analysis. Furthermore, we summarized the current knowledge of GNAS molecular pathology and updated the GNAS-locus-specific database. These results further expand the spectrum of GNAS mutations associated with PHP/PPHP and underline the importance of identifying such genetic alterations to supplement clinical evaluation and genetic counseling.

Neonatal hepatoblastoma in a newborn with severe phenotype of Beckwith-Wiedemann syndrome.

Beckwith-Wiedemann syndrome is an overgrowth disorder characterized by neonatal macrosomia, abdominal wall defects, macroglossia, renal anomalies, organomegaly, hypoglycemia, and cancer predisposition. Hepatoblastoma is the second most frequent tumor and periodic serum alpha-fetoprotein (αFP) dosage is the cornerstone of the tumor surveillance for its early detection. In this report, we describe the outstanding case of a Beckwith-Wiedemann syndrome (BWS) newborn with severe phenotype and paternal chromosome 11 uniparental disomy (UPD11) associated with a high tumor risk. Based on the clinical picture and previous reports, a close monitoring of αFP was commenced. The marker was normal immediately after birth, but rapidly raised in 20 days, leading to the diagnosis of an extremely aggressive hepatoblastoma. The latter was successfully treated with pre-surgical reductive chemotherapy, gross total mass resection, and subsequent chemotherapy. Based on this observation, the tumor surveillance routinely suggested every 3 months should be more intense and with closer time intervals in newborns with severe BWS phenotype. We suggest monitoring neonatal αFP every 20 days in such cases.