ESPE Abstracts

Background: Heterozygous GNAS inactivating mutations cause pseudohypoparathyroidism type Ia (PHP-Ia) when maternally inherited and pseudopseudohypoparathyroidism (PPHP)/progressive osseous heteroplasia when paternally inherited. Mutations on the paternal, but not the maternal, GNAS allele are associated with intrauterine growth retardation (IUGR). Moreover, birth weights were lower with paternal GNAS mutations affecting exons 2–13 (including XL and Gαs) than with exo...

Background: GNAS gene is a complex imprinted locus, resulting in the expression of at least four transcripts (XL, NESP55, A/B and Gsα) characterized by their specific exon 1 and common exons 2-13. While Gαs is biallelically expressed in most tissues, XL is only expressed from the paternal allele. Maternally inherited, loss-of-function mutations affecting those GNAS exons that ...

Background: Homozygous or compound heterozygous mutations of gene CYP24A1 have recently been reported to cause idiopathic infantile hypercalcemia due to increased intestinal absorption of calcium. However, an autosomal dominant transmission with partial penetrance of the trait was also suggested.Objective and hypotheses: Evaluation of the frequency of CYP24A1 mutation and evaluation of the impact of heterozygous mutation on calcium meta...

Background: Patients affected by pseudohypoparathyroidism type 1b (PHPI-b) develop resistance to PTH leading to hypocalcemia and hyperphosphoremia, which is often associated with resistance to TSH. PHP-Ib is associated with methylation changes at one or several differentially methylated regions (DMRs) within the GNAS complex locus, located at 20q13.2–13.3. This locus gives rise to several different transcripts (NESP55, XL, A/B), with varying patterns of imprinted expressi...

Background: Pseudohypoparathyroidism type 1A (PHP1A) and PseudoPHP are caused respectively by maternal and paternal mutations involving those GNAS exons that encode the alpha-subunit of the stimulatory G protein (Gsα). Common to different forms of PHP1B is a loss-of-methylation (LOM) at one or several maternal GNAS exons, which likely reduces Gsα expression in certain tissues. In most autosomal dominant PHP1B variants (AD-PHP1B), LOM is restricted t...

Vitamin D dependency rickets type 1B (VDDR-1B) is a rare condition classified as rickets due to inadequate 25-hydroxylation of vitamin D. In this study, we describe rickets and loss-of-function CYP2R1 mutations in 6/10 individuals tested from two unrelated families. Five patients in family 1 (F1) have homozygous L99P mutations; while one member of family 2 (F2) has novel homozygous mutations at G42_L46del insR. The mutations, as well as another variant M248I found in ...

Introduction: Rare mutations of the ESR1gene, encoding the estrogen receptor alpha (ERα), have been shown to cause estrogen resistance in humans. To date, there are no effective therapeutic options. We report the case of a new inactivating mutation of ERα and provide evidence for a partial restoration of biological effects of estrogen.Methods: We performed clinical and biological phenotyping of the index case and sequenced the ESR1...

Context: The mouse ERα−/− knock-out model and rare human ESR1 gene mutations identified to date have demonstrated crucial role of ERα in control of energy homeostasis and glucose metabolism. Subjects with ERα deficiency show features of estrogen resistance (ESTRR) with continuous linear growth in adulthood.Patient: We describe a 20-year-old female, with unknown family history, who presented...

Background: Nephrogenic syndrome of inappropriate antidiuresis (NSIAD) is a very rare clinical condition. Patients suffer from hyponatremia, hypo-osmolality with inappropriately elevated urinary osmolality and undetectable AVP levels. Activating mutations of AVPR2, the vasopressin receptor type 2 (V2R), induce a prolonged signaling of the intracellular cAMP/PKA pathway and cause NSIAD in patients.Objective and hypotheses: To describe a new phenotype in a...

Background: SHOX and enhancer regions on PAR1 disorders have variable phenotypic consequences such as idiopathic short stature (ISS) and Leri-Weill Dyschondrosteosis (LWD).Objective and hypotheses: The aim of this observational multicentric study was to describe phenotypes and genotypes of a large population with mutation on SHOX and adjacent regions and to identify a possible phenotype–genotype correlation.M...