ESPE Abstracts

Background: Pseudohypoparathyroidism type 1b (PHP1b) is caused by epigenetic errors on the maternal GNAS allele at differentially methylated regions (DMRs) associated with exons A/B, XL, and NESP that lead to reduced production of Gαs transcripts most notably in the renal proximal tubule and thyroid follicular cells. Most PHP1b cases appear sporadically, few of which can be explained by paternal uniparental disomy involving chromosome 20q, leading to global methy...

Background: Pseudohypoparathyroidism type 1a (PHP1a) is characterized by Albright hereditary osteodystrophy (AHO) and multi-hormone resistance, most commonly to parathyroid hormone (PTH) and thyroid-stimulating hormone. This rare disorder is caused by inactivating mutations involving exons 1–13 of the imprinted GNAS gene that encodes the alpha-subunit of the stimulatory G protein (Gαs). Due to paternal imprinting of Gαs transcripts, GNAS mutati...

Context: Bartter syndrome (BS) is a group of rare autosomal-recessive tubulopathies characterized by hypokalemic, hypochloremic metabolic alkalosis in which the primary defect is a deficiency of transporters involved in sodium chloride reabsorption. Type 2 BS results from a defect in the renal outer medullary potassium channel encoded by the KCNJ1 gene. Type 2 BS presents with polyhydramnios, intrauterine growth retardation, prematurity, failure to thrive, pol...

Background: Hypophosphatemic rickets (HR) is most commonly X-linked or autosomal dominant, but autosomal recessive (AR) forms have been described. ARHR1 (DMP1) and ARHR2 (ENPP1) share identical biochemical characteristics of excessive renal phosphate wasting due to increased circulating levels of the phosphatonin FGF23 and low serum levels of 1,25(OH)2D. By contrast, in hereditary hypophosphatemic rickets with hypercalciuria (HHRH) phosphaturia is ...

Background: Hypoparathyroidism may manifest either as an isolated disorder or as a component of a more complex syndrome. Molecular genetic studies indicate that mutations in PTH, CASR, GCM2 and GNA11 are causes of isolated hypoparathyroidism (IH) and mutations in GATA3, TBCE, FAM111A, AIRE and TBX1 are associated with different complex syndromes with hypoparathyroidism.Objec...

Background: Generalized lymphatic anomaly (GLA) is a rare congenital disorder characterized by aggressive proliferation of dilated lymphatic vessels. The etiology of GLA is poorly understood.Objective and hypotheses: To identify the underlying genetic basis for GLA.Method: Exome sequencing (ES) was performed in two families, including a multigenerational family (family-1) with six affected members. RNA-seq was performed on skin bio...