Association of GNAS imprinting defects and deletions of chromosome 2 in two patients: clues explaining phenotypic heterogeneity in pseudohypoparathyroidism type 1B/iPPSD3

摘要

BackgroundThe term pseudohypoparathyroidism (PHP) describes disorders derived from resistance to the parathyroid hormone. Albright hereditary osteodystrophy (AHO) is a disorder with several physical features that can occur alone or in association with PHP.The subtype 1B, classically associated with resistance to PTH and TSH, derives from the epigenetic dysregulation of the GNAS locus. Patients showing features of AHO were described, but no explanation for such phenotypic heterogeneity is available.An AHO-like phenotype was associated with the loss of genetic information stored in chromosome 2q37, making this genomic region an interesting object of study as it could contain modifier genes involved in the development of AHO features in patients with GNAS imprinting defects.The present study aimed to screen a series of 65 patients affected with GNAS imprinting defects, with or without signs of AHO, for the presence of 2q37 deletions in order to find genes involved in the clinical variability.